SAT 2 Biology E/M Guide

Molecules of Biology

‣ Atoms form in reactions to form molecules. ‣ Molecules with different atoms are compounds. ‣ Molecules with a single type of atom are elements. ‣ Reactants ⟶ products ‣ Organic chemistry deals with molecules that contain carbon except CO2. ‣ 4 important types of organic macromolecules. ‣ Polymers are strings of repeated monomers.

NH2

H

O

C

C

OH

‣ Proteins are polymers of amino acids. ‣ There are 20 amino acids. The blue section is the amino group (NH2). The red part is the carboxyl group (COOH). ‣ The green part is the side-chain. Each of the 20 amino acids has a different R group. ‣ Amino acids combine to form protein. The bonds formed are peptide bonds and are formed by dehydration synthesis. H2O is removed to join them together. ‣ Peptide bonds can also be broken in a hydrolysis process; water is added to the structure. H O H H O C R

C

H HO OH

C

N

OH H

C

C

OH

R ‣ ‣ Forming proteins: dehydration; Breaking proteins: hydrolysis ‣ The monomer for a carbohydrate is a saccharide. ‣ Carbohydrates have only carbon, hydrogen and oxygen. ‣ Single saccharide carbohydrates are monosaccharides. ‣ Monosaccharides have a ratio of CnH2nOn. ‣ Glucose and fructose have C6H12O6

C

H

C

OH

C

H

H

C

HO

C

H

C

OH

H

C

OH

H

C

OH

H

C

OH

H

C

OH

H

C

OH

H HO

H

R

NH2

‣ They are different because of a differently located double bonded oxygen. O O

H

‣ In glucose, the double bonded oxygen is on the top carbon. In fructose, it is on the second carbon from the top. ‣ Glucose can also form a ring structure. ‣ Disaccharides are formed by the linking of two monosaccharides. ‣ Maltose is formed by a dehydration synthesis with two glucose. Water is lost, so the formula is C12H22O12. ‣ Sucrose is formed by a dehydration synthesis with one fructose and a sucrose. The formula is also C12H22O12. It is table sugar. ‣ Polysaccharides have multiple monosaccharides. ‣ As they are large chains, polysaccharides are good ways of storing glucose. ‣ Animals store glucose in the form of glycogen. ‣ Plants store glucose in the form of starch. ‣ Cellulose is another polysaccharide that forms cell walls in plants. ‣ The monomer for a lipid is a hydrocarbon. They function as energy storage compounds. H ...

C

...

H ‣ They form really long chains of hydrocarbons. ‣ They are hydrophobic and nonpolar. ‣ Triglycerides have three fatty acids bonded to a glycerol molecule.

H

O

H

H

H

C

O C

C

C

C

H

H

H

O

H

H

H

O C

C

C

C

H

H

H

O

H

H

H

O C

C

C

C

H

H

H

H

H

C

H

C H

‣ Steroid hormones are derived from cholesterol. ...

...

‣ The monomers of nucleic acids are nucleotides. They are made of a phosphate, a sugar, and a base.

...

‣ Fatty acids (purple) are hydrocarbon chains with a carboxyl at the end. ‣ Glycerol (red) molecules are alcohols with three carbons ‣ The body stores fat in the form of triglycerides. ‣ Phospholipids are like triglycerides, but one fatty acid is replaced by a phosphate group (PO32–) O

H H

C

‣ The four bases in DNA are adenine, guanine, cytosine, and thymine. ‣ DNA is double-stranded and forms a double helix.

O

P

O–

O–

H

H

C

C H

O

O

O

H

H

H

C

C

C

C

H

H

H

O

H

H

H

C

C

C

C

H

H

H

...

...

‣ The phosphate group (yellow) is hydrophilic and polar.

‣ Cholesterol is a special type of lipid where hydrocarbons form rings. They are found only in animal cells.

‣ The complementary bases are A-T and C-G. ‣ The bonds between the base pairs are hydrogen bonds. ‣ Adenine and thymine are held together by 2 bonds. Cytosine and guanine are held together by 3 bonds. ‣ Ribonucleic acid is similar to DNA, but is singlestranded. ‣ Its sugar is ribose, and in place of thymine it has uracil.


SAT Biology E/M Subject Test Review Guide • Page 2

Cells

‣ A cell has three main areas: the cell wall (and/or membrane), the cytoplasm, and the nucleus. ‣ Plants have cellulose cell walls. ‣ Bacteria have cell walls of peptidoglycan. ‣ Fungi have cell walls of chitin. ‣ Animal cells don’t have cell walls. ‣ The cell membrane is made of lipids and proteins. The main lipids are phospholipids. ‣ The phospholipids have hydrophilic/polar phosphate heads and nonpolar fatty acid tails. ‣ Cell membranes are lipid bilayers which are selectively permeable; they only allow some to go through. ‣ Diffusion is the movement of a substance from an area of high concentration to an area of lower concentration until there is an equilibrium. Hydrophobic molecules can cross this way. ‣ Facilitated diffusion is diffusion with hydrophilic molecules that can’t cross the membrane without help from certain protein channels. ‣ Active transport is the transport of substance from a lower concentration to a higher concentration. It requires energy. ‣ Bulk transport is the movement of larger items across the cell membrane. ‣ Endocytosis moves substances into the cell. The cell forms a vesicle around the object and eats it in. Phagocytosis is endocytosis for particles, and pinocytosis is for liquids. ‣ Exocytosis is the opposite of endocytosis. ‣ Osmosis is the movement of water across a concentration gradient. Water’s concentration gradient is opposite to the solute’s gradient. Higher concentration of water = lower conc. of solutes. ‣ A hypertonic solution has more particles outside and thus less water outside. Water will move out, causing the cell to shrivel. ‣ A hypotonic solution has more water outside. Water will enter, causing the cell to swell up. ‣ An isotonic solution has the same concentration inside and outside of the cell. ‣ The cytoplasm holds the organelles of an eukaryotic cell. ‣ All organelles but the ribosome are membranebound. ‣ The vacuole stores wastes and other material. ‣ Ribosomes are used for protein synthesis.

‣ The smooth endoplasmic reticulum transports substances around the cell. ‣ The rough ER has ribosomes on them. They synthesize special proteins. ‣ The Golgi apparatus sorts of packages proteins made by ribosomes on the ER. ‣ Mitochondria are double-membrane bound and produce ATP in cellular respiration. ‣ Lysosomes digest substances and old organelles. ‣ Centrioles help in making the spindle for mitosis. ‣ The nucleus is double-membrane bound and contains genetic material such as DNA. ‣ The nucleolus is the site of ribosome synthesis. ‣ The cell membrane controls what leaves and enters. ‣ Enzymes are organic molecules that help in chemical reactions. Catalysts increase the rate of reaction in chemical reactions. ‣ Enzyme catalysts are reusable and not used up in a reaction. ‣ Reactants bind into the active sites of enzymes. ‣ Only a certain enzyme can catalyze a certain reaction. This follows the “lock and key” model. ‣ Enzymes are specific. ‣ Substrates are the reactants in an enzymecatalyzed reaction. ‣ Enzymes are proteins with specific 3D shapes. They can be denatured and make them unable to catalyze reactions. ‣ Heat and pH are two ways of denaturing enzymes. ‣ Coenzymes help enzymes function. Vitamins are examples of coenzymes.

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SAT Biology E/M Subject Test Review Guide • Page 3

Cellular Respiration

‣ The goal of cellular respiration is to create adenosine triphosphate (ATP). ‣ ATP has a molecule of adenosine bonded to three phosphates. A lot of energy is stored in the bond that holds the third phosphate. ‣ When energy is needed, the bond will be hydrolyzed (broken), to form adenosine diphosphate and a molecule of phosphate. ‣ C6H12O6 + 6O2 ⟶ 6CO2 + 6H2O + ATP ‣ Not all energy released is in the form of ATP. They are instead stored as electrons in electron carriers. They will accept these electrons to be reduced until they can be used to make ATP. ‣ NAD+ + H+ ⟶ NADH (2e) ‣ FAD + 2H+ ⟶ FADH2 ‣ The first step is glycolysis in the cytoplasm. A molecule of glucose is split into two molecules of pyruvate. ‣ 2 ATP are used at first, but 4 ATP are produced. 2 NAD+ are also reduced to 2 NADH. ‣ Glycolysis is anaerobic. ‣ C6H12O6 + 2ATP + 2NAD+ ⟶ 2 Pyruvate + 4ATP + 2NADH ‣ The pyruvate dehydrogenase complex is a group of enzymes that helps the pyruvate enter the Krebs cycle. ‣ It removes a carbon from pyruvate as CO2 and attaches coenzyme A. NADH is produced. ‣ Since glycolysis yields 2 pyruvate, two molecules of acetyl CoA and NADH are produced, while two molecules of CO2 are released. ‣ PDC is an aerobic process. ‣ The Krebs cycle follows the PDC. It’s also known as the citric acid cycle. ‣ Acetyl CoA combines with oxaloacetic acid to form citric acid, which is broken down a carbon at a time (CO2 released). ‣ It eventually is rearranged to form oxaloacetic acid again. ‣ 3 NADH, 1 FADH2, and 1 ATP are made in each cycle. (Two cycles for one glucose molecule) ‣ This is also an aerobic process. ‣ Electron transport and oxidative phosphorylation return aim to oxidize the carriers and to use the electrons to make ATP. ‣ Electron transport is aerobic.

‣ Oxygen is the final electron acceptor. It forms water with hydrogen. ‣ In the ETC, NADH and FADH2 pass down electrons to carriers which finally give it to oxygen. ‣ The electron acceptors use the energy of the electrons to pump H+ into the inter mitochondrial membrane. ‣ This makes a H+ gradient. The ions cannot diffuse regularly because they are charged and need to go through facilitated diffusion. ‣ The ATP synthase lets the ions return to the matrix, and energy is used to phosphorylate ADP to ATP. ‣ About 36 ATP is made for each molecule of glucose. Process

Location

Uses

Net Yield 2 Pyruvate 1 Glucose Glycolysis Cytoplasm 2 ATP 2 ATP 2 NADH 2 Acetyl CoA PDC Mito. matrix 1 Pyruvate 2 NADH 2 CO2 3 NADH Krebs 1 FADH2 1 Acetyl CoA cycle Mito. matrix 1 ATP 1 Oxaloacetate (1 cycle) CO2 Oxaloacetate NADH Mito. ~36 ATP ETC FADH2 membrane H2O O2

‣ Without oxygen, the electron carriers cannot be oxidized, so PDC and the Krebs cycle shut down. ‣ Fermentation is the regenerating of empty electron carriers. ‣ In fermentation, NADH reduces pyruvate into different molecules. NADH becomes NAD+. ‣ In yeast, pyruvate is reduced into ethanol and CO2 is released in the process of alcoholic fermentation. ‣ In muscle cells, pyruvate is reduced to lactic acid in the process of lactic acid fermentation. ‣ Both of them only produce 2 ATP from glycolysis, and the end products are not beneficial. ‣

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SAT Biology E/M Subject Test Review Guide • Page 4

‣Transcription and Translation

‣ The cell nucleus contains genetic information. ‣ Chromosomes are bundled DNA in the nucleus. ‣ Prokaryotic DNA is in a single circular chromosome. ‣ DNA can replicate, so that cells can divide. ‣ There are four steps of DNA replication: 1.The double helix unwinds and the strands separate. 2.DNA polymerase form second strands by getting free nucleotides to bind to the parent strands. 3.Hydrogen bonds form. 4.The DNA molecules twist into helices. ‣ Each DNA strand is a template for the complementary strand. ‣ Non-sex cells are somatic cells. A person has 46 chromosomes in their somatic cells. Each person has different chromosomes (except for identical twins). ‣ Each somatic cell has 23 pairs of chromosomes. A set of 23 comes from the father, and the other 23 come from the mother. They form homologous pairs. ‣ Diploid cells have two sets of chromosomes (each has a homologous pair). ‣ Human cells are diploid. ‣ DNA carries instructions for making proteins. ‣ Genes are DNA parts that carry instructions for protein synthesis. ‣ DNA controls RNA synthesis, which controls protein synthesis. ‣ DNA is transcribed to RNA, which is translated into protein. ‣ DNA unwinds in transcription, and one of the strands is used as a template. ‣ RNA polymerase creates a complementary strand, but instead of thymine on the RNA strand, uracil is added. ‣ After transcription, the RNA is set free. Only a part of the DNA is transcribed. ‣ Transcription occurs in the nucleus. ‣ mRNA is messenger RNA. It carries information from the DNA to the ribosomes. ‣ rRNA is ribosomal RNA. It interacts with ribosomes and ribosomes are made of them. ‣ tRNA is transfer RNA. They carry amino acids.

‣ A sequence of three nucleotides is a codon. The Genetic Code is the dictionary for protein translation. ‣ There are 64 codons (of ACUG). ‣ The codons are read in a nonoverlapping way, so that something like AUGGCACAGCUU would be read AUG GCA CAG CUU. ‣ AUG (methionine) is the start codon. ‣ UAA, UGA, UAG are the stop codons. ‣ tRNA is a clover shape, with an anticodon loop. This anticodon can pair with the codons on the mRNA. ‣ The anticodon is complementary to the codon with a base pair. AMINO

anticodon

‣ ‣ So if an mRNA has the codon CUU (leucine), then the anticodon is GAA. ‣ The ribosome synthesizes protein. ‣ There are two places on the ribosome to bind: the P-site (peptide site) and the A-site (amino site). ‣ The mRNA binds so that the first codon is in the P-site and the second in the A-site. ‣ When the tRNA brings the appropriate amino acid, a peptide bond would form between them. ‣ The first tRNA is released again, and the ribosome moves one codon, so that the codon in the A-site is now in the P-site. This allows a new codon to move in for another peptide bond to form. ‣ The final tRNA is released when a stop codon appears in the A-site. codon

amino

‣

PA

codon codon anti

anti

amino

amino

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SAT Biology E/M Subject Test Review Guide • Page 5

Mitosis and Meiosis

‣ Cell division is mitosis. ‣ Somatic cells have 23 pairs of homologous chromosomes. ‣ Before mitosis begins, all chromosomes have to replicate. ‣ Interphase is when chromosomes replicate. The cell still carries out normal activities, but is not actively dividing. ‣ After interphase, each chromosome and its duplicate are held by a centromere. ‣ An individual part of a chromosome is called the chromatid. Two of these are held by the centromere. ‣ At the end of interphase, each of the 46 chromosomes have doubled. There are still 46 chromosomes, but each of them have two chromatids. ‣ The first step is prophase. Centrioles move to the opposite sides of the cell, forming the mitotic spindle. ‣ These fibers attach to the centromeres of the chromosomes so they can be moved. ‣ The nuclear membrane starts to break up. ‣ The second step is metaphase. ‣ Chromosomes line up at the equator (metaphase plate). ‣ The third step is anaphase. The chromatids split so each chromosome only has one chromatid. ‣ Each of these chromosomes move to the opposite poles of the cell. ‣ The cell begins to split into two. It pinches at the cleavage furrow. ‣ The fourth step is telophase. ‣ A nuclear membrane reforms in each cell and there are two daughter cells, each having 46 chromosomes. ‣ The cytoplasm divides during cytokinesis. ‣ In plant cells, mitosis only occurs in meristems. The apical meristem is found at the tip of the stem and roots. ‣ The lateral meristem allows widening of plants. ‣ In the past, the one-gene-one protein theory said that each gene corresponds to a single protein. ‣ A chromosome is a long piece of DNA, which contains many genes. ‣ When a gene makes a protein, the gene is expressed.

‣ A set of 23 chromosomes came from your mother from an ovum (egg), and another set from your father from a sperm. ‣ These gametes have only 23 chromosomes, so they are haploid (n). Somatic cells are diploid (2n). ‣ Sex cells undergo meiosis. ‣ The zygote formed from a fertilized egg is diploid. ‣ In the beginning of meiosis, the cell still undergoes interphase DNA replication. ‣ Meiosis I has four phases. It differs from mitosis because homologous pair up in a process called synapsis. ‣ In prophase I, the chromosomes pair up with their homologous pair. When it is done, there are only 23 pairs of replicated chromosomes, each containing four chromatids (tetrad). ‣ The chromosomes condense, the membrane disintegrates, and segments on the homologous chromosomes are exchanged in crossing over. ‣ In metaphase I, the chromosomes line up on the equator. ‣ Chromosomes remain in their homologous pairs. There are 23 pairs instead of 46. ‣ The way that the chromosomes line up in metaphase affects the outcome of genetic information. ‣ The Independent Assortment of Chromosomes says that genes on non-homologous chromosome pairs are inherited independently. ‣ If n is the haploid number, and n is 4, then there are 2n = 16 combinations of chromosomes in the genes. ‣ Linked genes are on the same chromosomes and are inherited together, though crossing over could separate them. ‣ In anaphase I, centromeres don’t divide. The homologous pairs separate, and on each side there is a pair of chromatids and a centromere. ‣ In telophase I, the cells have 23 replicated chromosomes, not 23 homologous pairs. Each chromatid in a chromosome is identical. ‣ Meiosis II is similar to mitosis. Each cell has 46 replicated chromosomes, and so they split like mitosis–there is no pairing up and all that. ‣ The process ends with four haploid cells. ‣ Gametogenesis is the formation of sperm and ova. SAT Biology E/M Subject Test Review Guide • Page 6

‣ Formation of sperm is spermatogenesis, and it requires meiosis. ‣ Spermatogenesis begins with a diploid spermatogonium. ‣ Spermatogonium are in the seminiferous tubules of the testes. ‣ A diploid spermatogonium undergoes meiosis to make four sperm haploid cells. ‣ All four sperm are functional, unlike oogenesis which only produces one egg. ‣ Oogenesis deals with formation of the female egg cells ova. ‣ The first cell is the primary oocyte and are found in the ovary. ‣ The final cell is an ovum. ‣ Oogenesis results in a single ovum from a primary oocyte. ‣ Two daughter cells from meiotic division disintegrate. They have no organelles. These are polar bodies. ‣ An ovum is produced every month. ‣ Genetic variation results from independent assortment (metaphase I), crossing over (prophase I), and random fertilization.


SAT Biology E/M Subject Test Review Guide • Page 7

Genetics

‣ The phenotype is the organism’s traits. ‣ The genotype describes the genes responsible for a trait. ‣ A cat has blue fur. Its genotype would be BB, and the phenotype would be blue. ‣ The dominant trait decides the phenotype. The recessive trait will not be expressed if there is a dominant trait along with it. ‣ Uppercase letters represent the dominant, and lowercase letters represent the recessive. ‣ Alleles refer to genes that give rise to more than a version of a trait. ‣ Homozygous traits have the same alleles: BB or bb. ‣ Heterozygous traits have different alleles: Bb. ‣ Codominance is when two alleles for multiple alleles are both expressed. Example: AB blood. b

b

B

Bb

Bb

B

Bb

Bb

B

b

B

BB

Bb

b

Bb

bb

b

b

B

Bb

Bb

b

bb

bb

‣ Those are Punnett squares. ‣ BB x bb: 100% Bb ‣ Bb x Bb: 25% BB, 50% Bb, 25% bb ‣ Bb x bb: 50% Bb, 50% bb ‣ The sex chromosomes determine certain attributes. Non-sex chromosomes are autosomes. ‣ A male chromosome is the Y chromosome, and the female is the X chromosome. A male has the genotype XY and a female has XX. ‣ Gregor Mendel is the father of genetics who worked on the cross-breeding of pea plants. ‣ A monohybrid cross only deals with one trait. ‣ The law of dominance shows that the dominant allele can mask the recessive allele. F1

F2

T

T

t

Tt

Tt

t

Tt

Tt

T

t

T

TT

Tt

t

Tt

tt

‣ Even though all the organisms in the F1 generation seem tall, the alleles still segregate according to the law of segregation. ‣ Dihybrid crosses deal with two traits.

‣ When there are two traits: tall and short (T, t) and green and yellow (G, g). ‣ The law of independent assortment shows that the alleles can combine to these: TG Tg tG tg. TG

Tg

tG

tg

TG

TTGG

TTGg

TtGG

TtGg

Tg

TTGg

TTgg

TtGg

Ttgg

tG

TtGG

TtGg

ttGG

ttGg

tg

TtGg

Ttgg

ttGg

ttgg

‣ The Law of Dominance - one trait masks the effects of another trait ‣ The Law of Segregation - alleles can segregate and recombine ‣ The Law of Independent Assortment - traits can segregate and recombine independently ‣ We can tell if an organism with a dominant phenotype is homozygous or heterozygous by using a test cross (recessive). ‣ If no offspring is short (assuming the original is dominant-tall), the original is homozygous TT. ‣ If short plants are present, the original is heterozygous Tt. Sex-linked traits are traits with alleles on the sex ‣ chromosomes. Most of them are on the X chromosome because it is larger. ‣ Examples of X-linked traits: hemophilia, color blindness, and male baldness. ‣ Since a male has the X and Y chromosome, some traits cannot be masked. A female will only get these diseases when she is homozygous for the trait. ‣ Females heterozygous for X-linked recessive traits are carriers. ‣ An X-linked recessive trait cannot be passed from father to son. ‣ A pedigree shows the phenotype in a family over generations. ‣ Males are squares and females are circles. ‣ Recessive conditions skip generations. ‣ Population genetics is the study of allele distribution over time.

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SAT Biology E/M Subject Test Review Guide • Page 8

Evolution and Diversity

‣ Life appeared on Earth ~1 billion years ago. ‣ Early atmosphere made of hydrogen, ammonia, methane, and water. ‣ More intense climate in the past: lightning, volcanoes, UV. ‣ The heterotroph hypothesis theorizes that life began because of these conditions. ‣ This environment was simulated in a flask. ‣ Heterotrophs cannot synthesize their own food. ‣ Autotrophs can make their own food. ‣ Earliest organisms were anaerobic, current organisms are mostly aerobic. ‣ The early atmosphere did not have oxygen. ‣ A population’s gene pool is all the genes of a population. ‣ Each person in a population has a different gene set: genetic variability. Gene pools have different alleles. ‣ There can be a random mutation of DNA that somehow affects the DNA sequence, affecting the synthesis of RNA. ‣ Evolution is change in a population’s gene pool. ‣ Darwin observed in On the Origin of the Species some stuff about his theory of evolution: ‣ Each species produces more offspring than ca survive. ‣ The offspring compete for limited resources. ‣ Offspring with most favorable traits can survive and produce offspring. ‣ Geographic isolation - a new species may form when some individuals from a species are isolated from the rest. ‣ Fitness is an organism’s ability to produce surviving offspring. ‣ Different species cannot produce fertile offspring. ‣ The formation of new species by evolution is speciation. ‣ Divergent evolution is the process where two populations with similar traits changed as the result of multiple factors, making their traits different over time. ‣ Species that share a common ancestor usually have really similar homologous structures, such as the forelimbs of mammals. They might, however, have different functions. ‣ Convergent evolution causes two populations to become more similar to each other.

‣ Convergent evolution cannot result in speciation. ‣ Convergent evolution can result in analogous structures that don’t come from common ancestors. ‣ Sometimes important structures become unimportant. These are vestigial structures. ‣ Domain - Kingdom - Phylum - Class - Order Family - Genus - Species ‣ Scientists classify organisms based on their phylogeny (relationships). ‣ The science of classification is taxonomy. ‣ Carolus Linnaeus came up with the binomial nomenclature: Genus species. Domain Bacteria: prokaryotes and bacteria; it has one kingdom Eubacteria, which includes the blue-green algae Cyanobacteria. Domain Archaea: prokaryotes. There is a kingdom Archaebacteria and they lack nuclei and membrane-bound organelles (like Bacteria). They live in harsh environment. ‣ They are described as extremophiles and include the extreme halophiles (salty), extreme thermophiles (heat), and methanogens (methane gas). Domain Eukarya: Eukaryotes Kingdom Protista: Contains organelles which can form colonies. Can be uni- or multi-cellular. Protozoa are animal like, and algae are plant like. Phylum Rhizopoda (Amoebas)

Unicellular. They move with pseudopodia. They are found in soils and aquatic environment. Can be parasitic.

Phylum Apicomplexa (Sporozoans)

Animal parasites that can cause diseases. Can require multiple hosts for completion of life cycles.

Phyla Myxomycota / Acriasiomycota (Slime Molds)

Look like overgrown amoeba and have many nuclei

Phylum Ciliophora (Ciliates)

Unicellular organisms that use cilia for movement, such as paramecium.

Phylum Euglenophyta (Euglena)

Unicellular photosynthetic algae with flagella

Unicellular organisms with glasslike walls that live in Phylum Bacilariophyta freshwater/marine environments. (Diatoms) The walls are diatomaceous earths that can be a filtering medium. Phylum Phaeophyta (Brown Algae)

Seaweeds and are multicellular.

SAT Biology E/M Subject Test Review Guide • Page 9

Kingdom Plantae: Multicellular, eukaryotic, and photosynthetic. They have cell walls of cellulose. Instead of phylum, the word division is used. Division Bryophyta (Nonvascular Plants)

These plants don’t have xylem or phloem, so they have to live in damp areas. They need water for fertilization, and don’t have true stems, leaves, or roots.

Division Pterophyta (Ferns)

Earliest vascular plants and have the vascular tissue, true stems, leaves, and roots. They don’t have seeds, but have spores.

True vascular plants, and are mostly large evergreens. The Division Coniferophyta conifers are the cones that carry (Conifers) the seeds. The seeds are gymnosperms and don’t produce flowers. Division Anthophyta (Flowering Plants)

They are true vascular plants that make flowers and pollen.

> Class Monocots

They have single-seed cotyledons. Their leaf veins are parallel, and have parts in multiples of 3. The vascular bundles are scattered and they have a fibrous root system.

> Class Dicots

2 cotyledons, netlike veins, flower parts in multiples of 4 or 5, vascular tissue in ring, and taproot system.

Phyl. Platyhelminthes (Flatworms)

Bilateral symmetry and moderate cephalization (head). They can be nonparasitic (planaria) or parasitic (flukes, tapeworms).

Phylum Mollusca (Mollusks)

Soft-bodied with a hard shells. They have a foot, visceral mass (for major organs), and a mantle.

Phylum Annelida (Segmented Worms)

Closed circulation, mouth and anus, and excrete waste through metanephridia.

Phylum Arthropoda (Arthropods)

Most diverse phylum. Have jointed appendages, chitin exoskeleton, open circulatory tubules and eliminate waste through Malpighian tubules. Crustaceans, insects, and arachnids.

Phylum Echinodermata Sessile/slow-moving and have (Echinoderms) spiny exoskeletons. Phylum Chordata (Chordates)

Hollow notochord (flexible structure), and are mainly vertebrates.

> Class Chondrichthyes (Cartilaginous Fishes)

Flexible skeletons made of cartilage and breathe through gills, such as sharks.

> Class Osteichthyes (Bony Fishes)

True bone skeletons and breathe through gills, such as tuna.

> Class Amphibia (Amphibians)

Adapted to land and water. Eggs need to be laid in water, and have an aquatic larval stage but a terrestrial adult. Breathe through lungs or skin.

Division Zygomycota

They reproduce sexually and include molds and mycorrhizae

> Class Reptilia (Reptiles)

Div. Basidiomycota (Club Fungi)

Includes about 25,000 members, such as mushrooms and puff balls.

Thick, scaly skin for water loss prevention. Can live in dry area. Shelled eggs.

> Class Aves (Birds)

Tetrapods with forelimbs as wings. Endothermic.

> Class Mammalia (Mammals)

Endothermic, and have hair. They nourish young with mammary glands.

Kingdom Fungi: Eukaryotic, multicellular organisms with chitin cell walls. (Yeast is unicellular). They have a filamentous structure and have multiple nuclei. They are heterotrophic, and are often decomposers.

Kingdom Animalia: Eukaryotic, multicellular, and heterotrophic Phylum Porifera (Sponges)

Sessile and have a perforated body wall with two layers of cells. Water enters the body wall and the food in it is taken in.

Phylum Cnidaria (Coelenterates)

Two cell layers, central saclike digestive system and have radial symmetry. Examples: hydra, jellyfish.

‣ The evolutionary order of chordates: fish, amphibians, reptiles, birds, mammals.


SAT Biology E/M Subject Test Review Guide • Page 10

Microorganisms

‣ Fungi are multicellular eukaryotes. ‣ Fungal cell walls are made of chitin. ‣ They can be multinucleate. ‣ Yeast are fungi, not prokaryote. ‣ Fungi cannot photosynthesize; they are heterotrophs. ‣ They secret hydrolytic enzymes to digest food because they are absorptive feeders. ‣ Fungi can reproduce in different ways. ‣ Asexual spores are like seeds that fall off the fungus to grow a new organism. ‣ Sexual spores are like sperm and ova that form new organisms. ‣ With vegetative growth, a part of the fungus breaks off to form a new one. ‣ A new fungus grows off the old fungus with budding. Yeast does this. ‣ Bacteria reproduce asexually with binary fission. ‣ The bacterium replicates its only chromosome and splits it in half. ‣ There is no genetic recombination in binary fission. ‣ Bacteria are single-celled and are prokaryotes. They don’t have membrane-bound organelles. ‣ The DNA is freely floating in a circle. ‣ Their cell walls are made of peptidoglycan. ‣ Bacteria can still mix up DNA in other ways: ‣ In transformation, bacteria can pick up extracellular new DNA. It is rare. ‣ bacteria + DNA ‣ In conjugation, bacteria replicate and donate some of its DNA to other bacteria through a pilus. ‣ bacteria + bacteria ‣ In transduction, a virus carries DNA from a bacterium to another bacterium. ‣ bacteria + virus A ‣ strain resistant to something will not be destroyed by it. (Denoted: ampr) ‣ A strain sensitive to something will be destroyed by it. (Denoted: amps) ‣ Saprobes are decomposing bacteria ‣ Parasites gain nutrition from hosts while damaging them. ‣ Symbionts are like parasites but they don’t harm the host. ‣ Cyanobacteria can undergo photosynthesis.

‣ Obligate aerobes need oxygen to survive. ‣ Obligate anaerobes are harmed by oxygen. ‣ Facultative anaerobes use oxygen but can also survive by fermentation without oxygen. ‣ An auxotroph requires supplementary nutrition. ‣ Non-auxotrophs are wild type. ‣ Wild type bacteria can synthesize what they need if they have a carbon source (i.e. glucose). ‣ Auxotrophic bacteria need extra substances because they might not be able to synthesize a certain amino acid. ‣ If it cannot synthesize a certain amino acid, it is denoted arg–. ‣ If it can synthesize something, it is denoted arg+. ‣ If something is denoted lac– it cannot grow on lactose. ‣ Many plants need nitrogen, but cannot use N2 and need either NO3– or NH4+. ‣ Nitrogen in soil comes from breakdown of organic material. Ammonifying bacteria convert the nitrogen to ammonium. ‣ Nitrogen-fixing bacteria convert gaseous nitrogen to ammonia, which is converted to ammonium in the soil, than to nitrate by nitrifying bacteria. ‣ Some nitrogen-fixing bacteria form a symbiotic relationship with plant roots. ‣ This relationship is mutualistic; both sides benefit. ‣ The bacteria live in the nodules in the roots. Legumes establish this relationship. ‣ Viruses aren’t considered alive. ‣ They have a protein coat called the capsid. ‣ They also have nucleic acid (the genome). ‣ They cannot reproduce on their own, so they need help. ‣ The viral life cycle begins with the attachment: a virus attaches to a host. ‣ In infection, the virus injects its genome into the host. ‣ There are two possible life cycles now. ‣ In the lytic cycle, the genome is transcribed and translated to make viral protein. ‣ The host DNA polymerase replicates the genome and are packaged into viral capsids. ‣ The host is lysed by an enzyme and the viruses destroy the host cell and new viruses leave to infect more. ‣ Viruses are parasites. SAT Biology E/M Subject Test Review Guide • Page 11

‣ In the lysogenic cycle, the genome is first integrated with the host’s genome and stays dormant. ‣ The viral genome is replicated when the host divides. ‣ After a certain time, the virus can start the lytic cycle. ‣ Animal cells have no cell wall, so viruses don’t have to break them apart. They can just escape through the membrane. ‣ When the virus leaves, it is coated in an envelope. ‣ Viruses with RNA genomes have more trouble in replicating. ‣ They cannot use DNA polymerase to replicate. It cannot replicate with the host’s RNA polymerase because it’s based off a DNA template. ‣ The virus uses RNA-dependent RNA polymerase to make a strand of RNA through an RNA template. ‣ The virus needs to have the enzyme in its capsid to inject or synthesize it in translation of genome. ‣ Retroviruses are RNA viruses that go through the lysogenic life cycle. ‣ A DNA copy of the viral genome needs to be made first, which requires the RNA-dependent DNA-polymerase (or reverse transcriptase). ‣ The transcriptase creates DNA from RNA. ‣ Restriction enzymes recognize a DNA sequence and cut the DNA strand. ‣ Some bacteria use it to stop growth of viruses. The bacteria can have -CH3 to prevent the enzyme from destroying itself. ‣ Most restriction enzymes are palindromic. ‣ The enzyme EcoRI in E. coli recognizes:
 5’ – G | A A T T C – 3’
 3’ – C T T A A | G – 5’ ‣ EcoRI perform staggered cuts to produce sticky ends. The ends can be ligated to another DNA cut with this enzyme. ‣ In a blunt cut, the DNA is cut straight through, so that it can be ligated with any enzyme. ‣ A plasmid is a circular DNA found in bacteria or yeast. ‣ It is not part of the bacterial genome and can reproduce independently. It has restriction sites. ‣ In recombinant DNA, new DNA is made by splicing DNA.

‣ A restriction map maps the location of various restriction sites in a piece of DNA. ‣ First, you extract a sample of DNA. ‣ Then, you cut the gene out with a restriction enzyme. ‣ You can amplify the gene by putting the segment into a plasmid that has a site for the same restriction enzyme. ‣ This makes a plasmid with a certain DNA, so it can be grown in bacteria. ‣ Restriction enzymes help us cut and paste DNA into specific combinations. ‣ A vector can move DNA between species. Plasmids and viruses can help do this. ‣ DNA ligase helps glue DNA segments together.


SAT Biology E/M Subject Test Review Guide • Page 12

Anatomy Nervous

interprets information and controls body

Endocrine

hormones to control body functions

Circulatory

transports materials and cells

Lymphatic

captures/filters fluids to return to blood

Respiratory

O2 to CO2

Digestive

takes in and breaks down food for nutrients

Urinary

removes metabolic wastes

Skeletal

supports and protects the body, movement

Muscular

body movement

Skin

protection

Reproductive offspring production

‣ The nervous system consists of millions of neurons that carry impulses. ‣ The soma is the cell body. ‣ Things that stick off the body are processes. ‣ There are many dendrites and one axon.

‣ The branches off the cell is the dendrite, and the red boxes are the myelin sheaths. ‣ The dendrites receive impulse to passes to the axon. ‣ A polarized neuron is not carrying an impulse. The inside of the neuron is more negatively charged. ‣ When resting, they maintain a resting membrane potential of about -70 mV. ‣ The Na/K ATPase and the K leak channel maintain the RMP. ‣ The sodium-potassium pump uses ATP to move 3 Na ions out of cell and 2 K ions into the cell. ‣ There are also potassium leak channels that always let potassium leak out of the cell if there is a gradient. ‣ Since Na+ ions are pumped out, and K+ ions leak out, the inside is more negative than the outside. ‣ Neurons also have voltage-gate channels. ‣ They open when the cell membrane reaches a certain voltage. ‣ -50 mV is the threshold potential that will open these voltage gates.

‣ When the threshold potential is reached, sodium voltage-gated channels open. Sodium enters the cell, making the inside more positive. ‣ At about +35 mV, the sodium channels close and the potassium voltage-gated channels open. Potassium leaves the cell. ‣ The potassium channel closes at about -90 mV, and the Na/K ATPase and leak channels restore the RMP. ‣ The process above is the action potential. ‣ A polarized state is negative on the inside. When there is an action potential, depolarization occurs. After that, depolarization occurs. ‣ The axon has special Schwann cells that form myelin sheaths. ‣ Spaces between the sheaths are nodes of Ranvier. ‣ Myelin increases impulse travel speed. ‣ Only the nodes of Ranvier fire action potentials so the impulse jumps from node to node. ‣ The jumping conduction is saltatory conduction. ‣ After firing an action potential, there is a refractory period to prevent firing of a second potential. ‣ At the end of an axon, the impulse will go through a synapse to dendrites of another cell. ‣ Synapses use neurotransmitters to pass impulses. ‣ There is a small synaptic cleft between the two neurons. ‣ The terminal end of the first neuron has vesicles of neurotransmitters. The impulse causes vesicles of neurotransmitters to be released to the receptor of the second neuron, causing depolarization. ‣ Not all neurotransmitters can stimulate a cell and depolarize it. Others can inhibit it. The neuron will add up all the stimulatory and inhibitory input in a summation to decide whether an action potential will be fired. ‣ Common neurotransmitter: acetylcholine (ACh). ‣ The brain and spinal cord are made of neurons. They are the central nervous system. ‣ Neurons not in the CNS are part of the peripheral nervous system. ‣ Sensory neurons send information from sensory organs to the CNS. ‣ Motor neurons send information from the CNS to organs. ‣ Interneurons in the CNS connect the sensory and motor neurons. SAT Biology E/M Subject Test Review Guide • Page 13

‣ All action potentials are equal. ‣ The frequency of the action potentials firing determines the sensation a person feels. ‣ The CNS can be subdivided into smaller parts. ‣ The spinal cord is involved in reflex actions. ‣ The cerebrum is the conscious mind. Voluntary actions are made here. ‣ The cerebellum controls muscle movement and balance. ‣ The medulla controls involuntary acts such as blood pressure regulation. ‣ The hypothalamus deals with homeostasis. ‣ The PNS is also split into multiple divisions. ‣ The somatic nervous system is voluntary. It controls the skeletal muscles. ‣ It uses ACh as a neurotransmitter. A somatic motor neuron contracts muscles by binding to muscle receptors. ‣ The autonomic nervous system is autonomous and involuntary. We don’t have control: such as the heart, digestive organs, etc. ‣ The ANS can be split into more parts. The sympathetic division is the fight or flight system. ‣ It prepares the body for stress, by increasing rate and force of heartbeats, breath rate, etc. ‣ The neurotransmitter for the sympathetic division is norepinephrine. ‣ The parasympathetic division is the resting and digesting system. ‣ It is active when one is at rest, and decreases many functions. It stimulates digestive activity. ‣ The neurotransmitter here is acetylcholine. ‣ Organisms in the vertebrate group have similar systems. ‣ Arthropods and annelids have a ventral nerve cord and a brain. They are just cluster of nerve cells (ganglia) and there are neurons that branch from this. ‣ The endocrine system also controls the body, such as blood glucose and extracellular sodium regulation or puberty. ‣ It controls the body with hormones, chemicals that made by endocrine glands released into the bloodstream. ‣ Organs have receptors for certain hormones. ‣ Peptide hormones are amino acid-based and steroid hormones are cholesterol-based.

‣ Peptide hormones are small protein molecules. They bind extracellularly. They cause effects quickly by turning off or on certain enzymes. ‣ Steroid hormones are lipids and can bind intracellularly. They are slower because they can affect DNA transcription. Pituitary gland - controls many endocrine glands, and is controlled by the hypothalamus. Anterior pituitary gland - there are corresponding releasing hormones in the hypothalamus Growth hormone (GH)

targets all organs and helps them grow. In adults, they allow older cells to be replaced (cell-turnover)

Thyroid stimulating stimulates thyroid to make hormones hormone (TSH) stimulates gonads. Stimulates ovaries to release estrogen and stimulates testes to make testosterone stimulates ovaries to develop corpus Luteinizing hormone luteum, and stimulates testes to make (LH) testosterone. Adrenocorticotropic stimulates adrenal cortex to secret hormone (ACTH) hormones. stimulates mammary glands to make Prolactin breast milk Follicle stimulating hormone (FSH)

Posterior pituitary gland - hormones made in hypothalamus and sent to pituitary Oxytocin

contraction of uterus in childbirth and releasing of milk in mammaries

Antidiuretic hormone (ADH, helps kidney retain water vasopressin) Thyroid gland - located by the neck

increases rate of metabolism. It contains iodine. Iodine is needed for thyroxin production. Not enough Thyroxine iodine results in hypothyroidism which lowers metabolic rates, and hyperthyroidism increases it. removes calcium from blood and uses Calcitonin it to build bone. Parathyroid glands - located on thyroid glands Parathyroid hormone dissolves bone to release calcium into (parathormone) blood. Epinephrine and Prolong effects of sympathetic nervous norepinephrine system. Epinephrine has longer effect Adrenal glands (on the kidneys): adrenal cortex Glucocorticoids

cause liver to release new glucose (gluconeogenesis). They tell body cells to use fat instead of glucose. They are anti-inflammatory, like cortisol.

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For the kidneys. Aldosterone tells kidney to keep sodium in body. Pancreas (Islet of Langerhans) - secretes hormones and digestive enzymes Mineralocorticoids

Stimulates liver to convert glucose to glycogen for storage. Blood glucose falls. Stimulates liver to break down Glucagon glycogen to glucose. Blood glucose rises. Glycogenolysis. Gonads - the sex organs; ovaries for females, and testes for males Male sex steroids, such as testosterone Androgens which helps develop secondary sex characteristics Insulin

Estrogens and progesterone

Female sex characteristics and the menstrual cycle. (estradiol)

‣ Organisms with closed circulatory systems have blood in vessels. Organisms without these systems have blood (hemolymph) in body cavities. ‣ Blood plasma has water but also other dissolved items: glucose, albumin (a protein), fibrinogen, and lipoproteins. ‣ Plasma makes up about 50% of blood volume. ‣ Red blood cells make up 45% of blood volume. ‣ They have a protein called hemoglobin. ‣ Red blood cells don’t have a nucleus. ‣ Hemoglobin can bind oxygen. ‣ Hemoglobin is made partly of iron. ‣ If these blood cells can’t bind to enough oxygen because of anemia, you have less oxygen for cellular respiration. ‣ 5% are made of white blood cells. ‣ White blood cells called lymphocytes participate in immunity. ‣ B-cells make antibodies, which are markers that bind to foreign things. ‣ Helper T-cells help B-cells and T-cells divide. ‣ Killer T-cells destroy cells infected by viruses to prevent them from expanding. ‣ AIDS is caused by HIV, which kills the helper Tcells, preventing the other immune cells from fighting infection. ‣ Platelets are structures that help blood clotting. ‣ They secrete substances that convert fibrinogen, a protein into insoluble fibrin, which makes a net that clots up blood. ‣ It needs calcium, vitamin K, and other chemicals. ‣ Blood cells are made in the bone marrow.

‣ Membrane proteins determine blood type. ‣ The I gene has three alleles: IA, IB, and i. IA has type A protein, IB has type B, and i has none. ‣ IA and IB are codominant. ‣ Agglutination occurs when red blood cells clump together, because a body does not recognize the newly received proteins. Type

A B O AB

Genotype

Can Receive

Can Donate

IAIA, IAi A, O

A, AB

IBIB, IBi B, O

B. AB

ii

O

A, B, AB, O

IAIB

A, B, AB, O AB

Universal donor Universal recipient

‣ The heart is a pump for blood. ‣ Arteries carry blood away from the heart. ‣ The arterial blood pressure is higher. ‣ They have muscular walls. ‣ They regulate blood flow. ‣ They branch into arterioles and then to capillaries. ‣ Capillaries are the smallest blood vessels. ‣ They are the site of blood/tissue exchange. ‣ Capillaries merge to venules which become veins. ‣ Veins return blood to the heart. ‣ Veins have valves to prevent blood from backflow. ‣ They do not have muscular walls. ‣ They don’t regulate blood flow. ‣ The pressure on the artery side of a capillary has higher blood pressure. ‣ The vein side has a lower blood pressure, and some intercellular fluid returns to tissues. ‣ The lymphatic system is a vessel network that begins at tissues to veins. ‣ It captures extra fluid from the tissue and filters it before it returns to the blood. ‣ Lymph nodes are the places of filtration. ‣ They are clumps of white blood cells. ‣ Lymphatic vessels are like veins with valves and low pressure. ‣ Fluid in these vessels are lymph. ‣ Edema is the swelling of parts from trapped fluid. ‣ The heart has two atria on top and two ventricles underneath. SAT Biology E/M Subject Test Review Guide • Page 15

‣ The right side focuses on the pulmonary circuit and the left side focuses on the systemic circuit.

ATRIUM RIGHT

LEFT

VENTRICLE ‣ The pulmonary circuit takes blood from the body and pumps it to the lung for gas exchange. ‣ Path of blood: vena cava → right atrium → right ventricle → pulmonary artery → lungs (oxygenated!) → pulmonary veins → left atrium → left ventricle → aorta (largest artery) → body ‣ The atrioventricular valves are between the atria and the ventricles. ‣ The semilunar valves are between the ventricles and the arteries. ‣ The AV valves close before the semilunar valve, causing the lub-dub sound. ‣ A heart beat begins with the sinoatrial node in the right atrium. The contraction is systole, and the relaxation is the diastole. ‣ Fish have a 2 chambered heart. ‣ Amphibians have 3 chambered heart. ‣ Arthropods have an open circulatory system. ‣ Ventilation is moving air in/out of lungs. ‣ Exchanging O2 and CO2 is gas exchange. ‣ The conduction zone is only for gas exchange. ‣ The nose is for warming and filtering the air. ‣ Air goes down the pharynx (throat), the larynx (voice box), trachea (wind pipe) into two tubes. ‣ Each of these bronchi lead to the two lungs, where they split into bronchioles. ‣ The bronchial walls have mucus to trap dust. ‣ Small bronchioles have alveolus bubbles where gas exchange takes place. ‣ The alveoli walls are thin; capillaries surround it. ‣ Oxygen moves from the alveoli into blood, and CO2 moves to alveoli. ‣ The gases are hydrophobic. ‣ Blood pH is from about 7.35 to 7.45.

‣ Carbon dioxide cannot dissolve in water. ‣ It is converted to H2CO3 (carbonic acid) and to HCO3– (bicarbonate) which can dissolve through plasma. ‣ If blood pH is too low, we breathe faster to get rid of the carbonic acid. If blood pH is to alkaline, we breathe slower. ‣ The medulla oblongata in the brain monitors this and adjusts our respiratory rate. ‣ The diaphragm is the muscle of breathing. ‣ When relaxed, it curves up. When contracted, it flattens out and the chest cavity increases. ‣ The increase in volume = decrease in pressure, causing air to rush to lungs (inspiration). ‣ Relaxing the diaphragm pushes air out in expiration. ‣ The alimentary canal starts at the mouth to the anus. ‣ There are accessory organs that help the digestive process but are not part of the alimentary canal. ‣ The mouth takes in food and the teeth and tongue form the food into a bolus lump. ‣ Salivary glands secrete saliva with amylase to moisturize food. The amylase can digest starch. ‣ The bolus enters the esophagus into the stomach via peristalsis motion. ‣ The stomach is acidic because of the gastric juices. ‣ The gastric glands secrete pepsin to break down protein. ‣ HCl lowers the pH to activate pepsinogen in the pepsin to digest proteins. ‣ Food turns into chyme to enter the small intestine. ‣ The small intestine digests the most. ‣ The liver produces bile which is stored in the gallbladder. ‣ Bile is used to emulsify fat, not digest it. ‣ The pancreas secretes amylase for carbs, lipase for fats, protease for proteins, and also bicarbonate to neutralize the acidic chyme. ‣ The small intestine has villi and folds to increase the surface area. ‣ The nutrients are absorbed to the blood to the liver. ‣ Portal veins are veins from the intestinal capillaries. ‣ The hepatic portal system delivers nutrients from intestine to the liver. SAT Biology E/M Subject Test Review Guide • Page 16

‣ Digestion and absorption takes place in the small intestine. ‣ In the large intestine/colon, water is reabsorbed. ‣ Chyme solidifies into feces. ‣ The large intestine has both non-pathogenic and pathogenic bacteria. ‣ It supplies essential vitamin K. ‣ Amylase breaks carbs to glucose. ‣ Protease breaks protein to amino acids. ‣ Lipase breaks lipids into fatty acids and glycerol. ‣ Vitamins function as coenzymes, and there are some minerals that are important. Name

Function

Vit. A

Make retinal for sight night blindness

Vit. B

Vit. D

Cell resp, DNA replic. skin disorders, anemia scurvy, non-healing collagen wounds calcium absorption week bones, rickets

Vit. E

protect cell membranes anemia

Vit. K

blood clotting

Vit. C

Iron

hemoglobin strong bones / muscle Calcium contraction Iodine thyroxine

Deficiency

excessive bruising anemia rickets, osteomalacia decreased metabolic rate

‣ Waste products are filtered by the kidneys and eliminated in urine. ‣ The wastes are urea, uric acid, and creatinine. ‣ Nephrons are functional units of the kidney

‣ Blood enters the renal arteries to the kidneys. ‣ The glomerulus is a tiny knot of capillaries in the nephron, and sits in a Bowman’s capsule. ‣ Blood pressure force blood through these capillaries. Large cells left behind ‣ The filtrate travels thru nephron and is modified. ‣ Important substances are returned to blood. ‣ The filtrate turns into urine. ‣ Urine goes down ureter to be stored in bladder.

‣ Urine eliminated through the urethra. ‣ Reabsorption is taking stuff out of the filtrate. Glucose is reabsorbed. ‣ Secretion is taking substances out of the blood to add to the filtrate, such as toxins. ‣ It takes place in the proximal convoluted tubule. ‣ Water is reabsorbed in the loop of Henle. ‣ Salt leaves the filtrate and enters the kidney, creating a concentration gradient. ‣ The medulla (inner part of kidney) becomes saltier than the cortex. ‣ The filtrate enters the distal convoluted tubule, where more reabsorption and secretion occur. ‣ The process here is more specialized. ‣ Here, aldosterone controls the sodium reabsorption. ‣ The last part is the collecting duct that receives filtrate from many nephrons. ‣ Antidiuretic hormone makes the collecting dict permeable to water. ‣ ADH levels are high when the body is dehydrated so that the body can concentrate urine. ‣ Kidneys can regulate blood pressure by releasing renin which makes angiotensin II to constrict blood vessels. ‣ This can increase aldosterone levels which increases sodium reabsorption, water reabsorption, and then blood pressure again. ‣ Worms use metanephridia to remove nitrogenous wastes. Insects have Malphigian tubules. ‣ Vertebrates have endoskeletons. ‣ Other animals have exoskeletons. ‣ Bone is made of cells in a Ca-P matrix. It supports the body, supports organs, produces blood cells, and stores minerals. ‣ Cartilage is flexible and is like a shock absorber. ‣ Some structures are made of cartilage. ‣ Bonds are held to bones with ligaments. ‣ Cardiac muscle is found in the heart. Smooth muscle are found in the walls of organs. These are involuntary muscle. ‣ Skeletal muscle is attached to bone. ‣ Muscle is made of actin (long chains) and myosin (thick fibers). ‣ Actin and myosin form sarcomeres. ‣ Many sarcomeres form myofibril. ‣ Myofibril bundled with parts form a muscle cell. ‣ Muscle cells are organized into fascicles. SAT Biology E/M Subject Test Review Guide • Page 17

‣ Fascicles group to form a muscle. ‣ A muscle shortens as it contracts. ‣ The sarcomere contracts, not the actin/myosin. ‣ Z-lines are the end of sarcomeres. ‣ Myosin doesn’t touch the Z-lines. ‣ During contraction, myosin drags actin to the center of the sarcomere. ‣ Actin slides over the myosin, dragging the Z-line. ‣ This is the sliding filament theory.

‣ Skeletal muscle is striated. They attach to bone with tendons. ‣ Skin is the largest organ in the body. ‣ The epidermis is the thin layer of dead cells at the surface. ‣ The dermis has blood vessels, nerves, follicles, and glands. ‣ The hypodermic is a fat layer that insulates the body. ‣ The skin protects the body from friction, heat loss, water loss, infection, and radiation. ‣ Cold-blooded organisms are ectothermic. ‣ Warm-blooded animals are endothermic and have a constant body temperature. ‣ When the body temperature rises, the brain dilates dermis vessels so that heat can leave the body. Sweat is secreted. ‣ When the body temperature falls, dermis vessels contract, sweat production halts, and the body begins to shiver to raise temperature. ‣ Testes are found in the scrotum out of the body. ‣ Sperm is made in seminiferous tubules which form the vas deferens. ‣ The vas deferens connects with urethra to bring out sperm. ‣ Sperm and some other fluids make up semen. ‣ The ovaries make gametes; the uterus is for pregnancy. ‣ The uterine cycle has three phases. ‣ Menstruation is the shedding of the endometrium of the uterus. Estrogen/ progesterone levels are low. (Days 1-5) ‣ The proliferative phase is the rebuilding of an endometrium. Estrogen is secreted. (Days 6-13)

‣ In the secretory phase, the uterine lining is prepared for pregnancy. (Days 14-28) ‣ Blood vessels are added, and sugars are secreted to thee lining. Progesterone controls this. ‣ The ovarian cycle has three phases. ‣ The follicular phase is caused by FSH, which results in follicle development. (Days 1-13) ‣ A follicle is a maturing oocyte and cells. ‣ They result in rising estrogen. ‣ Ovulation is the release of the oocyte to the Fallopian tube. (Day 14). There is a LH surge. ‣ Follicle part forms corpus luteum which makes progesterone in the luteal phase. (Days 15-28) ‣ If the ovum is implanted, the embryo secretes human chorionic gonadotrophin (hCG). ‣ hCG prolongs corpus luteum lifetime to secrete more progesterone; endometrium doesn’t shed. ‣ hCG levels stay high for 3-4 mo. in pregnancy. ‣ Gametes are formed. ‣ The egg falls down Fallopian tube to meet sperm. ‣ The acrosome in sperm allows it to penetrate egg. ‣ A diploid zygote is formed. ‣ Cleavage is rapid mitosis of zygote which forms a morula. ‣ The morula hollows out into a blastocyst. ‣ The cell mass clumps to one side and forms the embryonic parts. The outer ring forms placenta. ‣ The blastocyst is implanted in the uterus. ‣ Embryonic stage 1 is gastrulation. ‣ The cell mass divides into germ layers. ‣ Endoderm becomes inner linings of body systems. ‣ The mesoderm becomes the non-gland organs and bones, heart, etc. ‣ The ectoderm forms external structures. ‣ The second stage is neurulation. ‣ The nervous system is formed. ‣ Other organs are also formed in this stage, called organogenesis. ‣ In the fetal stage, the baby grows. ‣ The yolk sac surrounds the yolk of an egg. ‣ Human eggs have little yolk. ‣ Others develop out of body; they need yolk. ‣ The amnion is a membrane which is filled with the amniotic fluid as a shock absorber. ‣ The allantosis becomes the umbilical cord. ‣ The chorion forms the embryo’s placenta and encloses other membranes.

!

SAT Biology E/M Subject Test Review Guide • Page 18

Plants

‣ Flowering plants are angiosperms.

‣ Photosynthesis is use of sunlight for food.

‣ The epidermis is the outer layer. ‣ The cuticle is a wax layer for protection. ‣ The palisade layer has most photosynthesis. ‣ The spongy cells has air pockets for gas exchange. ‣ The stomates help with gas exchange and water. ‣ They are controlled by guard cells. ‣ The chloroplast is double-membraned. ‣ The stroma is the interior fluid. ‣ The thylakoid are sacs that make up grana stacks. ‣ The thylakoid membranes have chlorophyll. ‣ 6CO2 + 6H2O + energy → C6H12O6 + 6O2 ‣ The light-dependent reactions convert solar energy to NADPH and ATP. ‣ Electrons are excited by sunlight which go down an electron transport chain to make NADPH. ‣ Water is split into hydrogen and ions. ‣ O2 is released, and H is used in the ATP synthase. ‣ The light-independent reactions take place in the stroma (Calvin cycle). ‣ Ribulose bisphosphate has 5 carbons. ‣ CO2 makes RuBP into some 6C compound, which breaks down into 2 3C glyceraldehyde-3phosphate (G3P). ‣ 1 G3P is used for glucose. Another remakes RuBP. ‣ Carbon fixation is plants making carbohydrates. ‣ Roots anchor a plant to the ground. ‣ Root hairs grow to increase surface area for absorption. ‣ Water and minerals are transported with xylem. ‣ Xylem tissues are made from tracheids and vessel elements. ‣ The phloem transports nutrients. They are made from sieve cells and companion cells. ‣ Sieve cells carry out transport. ‣ Companion cells help sieve cells with metabolism.

‣ The stamen is the male part. The anther (which makes pollen) is supported by the filament. ‣ Pollen is made from microspores and pollen grains can form two sperm. ‣ The pistil is the female part. It has a stigma, style, ovule, and ovary. ‣ The ovule forms megaspores which can make eggs and polar bodies. ‣ Pollen fall into a sticky stigma and germinates. ‣ The pollen tube grows from the style to the ovary. ‣ The pollen sperm fertilize: one with egg, another with a polar body. ‣ The fertilized egg becomes the embryo, and polar bodies become endosperm. ‣ The endosperm is a food-storing tissue. ‣ The ovule develops into seed, and the ovary becomes fruit, which protects the seed. ‣ The seed is released and regrows.


SAT Biology E/M Subject Test Review Guide • Page 19

Behavior

‣ Instinct is unlearned and inherited behavior. ‣ Fixed-action patterns are behaviors triggered by a specific stimuli. ‣ Baby ducks swim when they enter water. ‣ Imprinting is recognition of an object as mother. ‣ These patterns occur even if the stimulus isn’t a natural stimulus. ‣ Learned behavior require interaction w/ environment. ‣ Habituation is when a non-harmful stimulus is repeated until it gets ignored. ‣ Conditioning is when a stimulus is associated with a certain behavior. (Associative learning) ‣ Classical conditioning is the association of a stimuli with a response. ‣ Operant condition is learning that occurs with reward and punishment. ‣ Insight learning is the ability to figure out how to deal with situations. (Reasoning) ‣ Tropisms are turning behavior in response to stimuli. ‣ Phototrophism is growth of plant towards light. ‣ Positive gravitropism is the growth of roots down towards the Earth. ‣ Negative gravitropism is growth of stem up away from earth ‣ Gravitropism is also called geotropism. ‣ Thigomotropism is the growth of plant along a surface. ‣ Auxins are plant hormones that induce these tropism behaviors. ‣ An instinctive biological clock that makes an organism do something daily is a circadian rhythm. ‣ Pheromones are chemicals that are released by a member of a species that affect other members of the species. ‣ Hormones are released into blood to affect the organism that secreted it. ‣ Symbiosis is when species share living space. ‣ Mutualism is when both organisms benefit. Bacteria in intestines produce vitamin K and feed off our waste. ‣ Parasitism is when one organism benefits while harming the host. Tapeworms are parasites. ‣ Commensalism is when an organism benefits while the other is not effected.
 SAT Biology E/M Subject Test Review Guide • Page 20

Ecology

‣ Biological organization: cell < tissue < organ organism < population < community < ecosystem < biome < biosphere ‣ A population is a group of individuals in an area that share the same gene pool ‣ A species needs to be able to interbreed ‣ An individual can’t evolve; a population can. ‣ Exponential growth begins exponentially until a level where it cannot grow as rapidly ‣ However, the maximum population size is limited at the carrying capacity. carrying capacity

‣ A community is a group or populations in an environment. ‣ An organism’s niche is how it lives in its environment. ‣ If two populations have similar niches, there is competition. ‣ One population will win and grow, and the other will shrink. ‣ Predation is when a predator eats a prey. ‣ Predation can cause the prey to evolve. ‣ Coevolution is evolution based on interaction between two species. ‣ The primary producers begin the food chain. ‣ They are photosynthetic. ‣ The next are the primary consumers (herbivores) ‣ Then there are secondary consumers (carni- or omnivore). ‣ Then there are tertiary consumers. ‣ There are decomposers that eat the dead. ‣ There are more producers and less consumers. ‣ AAAA → BBBB on a food chain means that BBBB eats AAAA. (AAAA eaten by BBBB). ‣ Only about 10% of energy is transferred to the next level on the food change. 90% is lost in actions such as heat, respiration, etc.

‣ Ecological succession is the change in an ecological community. ‣ The first organisms that move into a new area are pioneer organisms. ‣ More organisms move in. ‣ The community with the final organisms is stable and is the climax community. ‣ Ecological succession is the continuous changes in a community. It takes place quicker than evolution and is not evolution. ‣ An ecosystem is the community with its surroundings. ‣ Evaporation is water escaping as vapor from a water source. ‣ Transpiration is water leaving from leaf stomates. ‣ Water cycle - vapor from plants and lakes form clouds that rain down into soil. The runoff go into oceans. The ocean water evaporates and condensate in clouds that precipitate over land.

‣ Carbon cycle - atmospheric carbon taken in via photosynthesis and enters the soil through root respiration. Plants are eaten by animals which respire, putting CO2 back into the air. The soil also has carbon that enters the atmosphere.

‣ Nitrogen is important in amino acids and protein. It needs to be taken in to plants in NO3–, and not N2. In the nitrogen cycle, N2 is fixed by bacteria and used by plants. Animals eat plants and dead SAT Biology E/M Subject Test Review Guide • Page 21

animals decomposed again. Oceanic Zone

The open ocean. Little nutrients but some phytoplankton. Large free-swimming animals. Divided into open water pelagic (photic + aphotic) zone and ocean bottom benthic zones. Lowest is abyssal zone.

Aquatic Biomes (Freshwater)

‣ Biomes are communities with their climates. As a whole, biomes make up the biosphere. Terrestrial Biomes Tundra

Found in the northern parts of NA, EU, and Asia. It has permafrost and there are few trees, only small shrubs. Several insects and a few mammals.

Taiga

Also known as the coniferous forests. There are many conifers, and are southward of tundras. There are small mammals and larger herbivores and carnivores

Deciduous Forest

To the south of the taiga. There is a lot of rain and a distinct hot/cold season split. There is great diversity, and the trees lose their leaves in winter.

Grasslands

Also known as the savanna. There are lowgrowing plants and some trees. There can be droughts and fires. Split into tropical and temperate. Insects are dominant herbivores.

Tropical Rainforest

Highest rainfall and the greatest diversity. Trees are tall and plants grow around them. There is a canopy layer and sunlight does not reach the lowest area.

Desert

Driest biome. Can be hot or cold. Organisms have to adapt to arid environment.

Littoral Zone

Near the shore of a lake. Many plants, amphibians, insects, some fish.

Limnetic Zone

Farther from shore and extend up to where light can penetrate. There are photosynthetic organisms and primary consumers.

Profundal Zone

Aphotic part of the lake. Nutrients float down to support the consumers in this area.

‣ The greenhouse effect is the increasing CO2 concentration in the atmosphere that can cause global warming, pattern changes, and melting ice caps. ‣ Ozone depletion is caused by using CFCs which can destroy the O3 layer. ‣ Acid rain is caused by SO2 and NO2 that destroy ecosystems. ‣ Desertification comes from the overgrazing of animals, and deforestation happens because forests are cleared. ‣ The use of toxic chemicals can pollute the environment. The situation is amplified by biomagnification. ‣ Destruction of habitats can reduce biodiversity.

Aquatic Biomes (Marine) Intertidal Zone

Land and water meet. Can be wet or dry depending on the tide. Clams, sea stars, snails, crabs, sponges.

The shore to the continental shelf. Coral Neritic Zone reefs can be found here. Seaweeds, crustaceans, fish.

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