digestion-Questions-Ib-TEST.pdf

Daniela Durán

IB DIPLOMA BIOLOGY PAST PAPER QUESTIONS ON

DIGESTION A Test •Answer Q’s 1 to 4 by drawing a circle around the best answer. •Answer the remaining questions in the spaces  provided. •Question 10 is for HL only. 46 •Total marks: HL SL 36

John Osborne October 2014

Diploma Biology 2013/2014/2015

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1.

Which of the following is correct regarding the enzymes listed in the table? Enzyme Amylase

Lipase

Protease

A. Substrate Polysaccharide Polysaccharide

emulsified fat

dipeptide or polypeptide

B. Substrate emulsified fat

dipeptide or polypeptide

polysaccharide polysaccharide

C. Product

amino acids

small polysaccharides polysacchari des or monosaccharides

fatty acids and glycerol

D. Product

small polysaccharides polysaccharides or amino acids monosaccharides

fatty acids and glycerol (Total 1 mark)

2.

What does the digestion of starch by amylase produce? A.

Lactose

B.

Sucrose

C.

Galactose

D.

Maltose (Total 1 mark)

3.

In the digestive digesti ve system, enzyme A has an optimum pH of 1.5 and enzyme B an optimum  pH of 7. What are the possible substrates of these enzymes? Enzyme A

Enzyme B

A.

proteins

amino acids

B.

lipids

proteins

C.

carbohydrates carbohydrates

lipids

D.

proteins

lipids (Total 1 mark)

4.

Two cellular activities that support human life are absorption and assimilation. What is needed for assimilation but not for absorption? A.

Enzymes to synthesize synthesi ze new molecules

B.

Blood capillaries

C.

Dissolved nutrients

D.

Microvilli (Total 1 mark)

Diploma Biology 2013/2014/2015

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5.

The diagram below shows a transverse section of the ileum.

[Source: P H Raven and G B Johnson,  Biology,  Biology, (2002), 6th edition, McGraw-Hill, page 1024]

(a)

(i)

State the name and function of the structures labelled 1 and 2.

1:

Villus, increase intestinal absorptive surface area

2:

Lacteal, collect absorbed triglycerides and cholesterol (2)

(ii)

Distinguish between the muscles labelled 3 and 4. Muscle 4 is a circular muscle while Muscle 3 is a longitudinal l ongitudinal muscle. (1) (Total 3 marks)

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6.

Draw a labelled diagram of the digestive system. (Total 5 marks)

Diploma Biology 2013/2014/2015

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7.

Carbohydrates are one of the constituents of a balanced diet in humans, (a)

Carbohydrates can be used as a substrate in cell respiration. (i)

State one other constituent of human diets that t hat can be used as a respiratory substrate. Water (1)

(ii)

Outline two uses of carbohydrates carbohydrates in the human body, other than as a respiratory r espiratory substrate. 1. Carbohydrates can be broken down into smaller saccharides and used in the  production of new proteins proteins 2. Carbohydrates can be found in the t he cytoplasm of cells (2)

(b)

Monosaccharides Monosaccharides are useful if energy energy is needed needed rapidly, but polysaccharide polysaccharidess are are a better form of carbohydrate if energy is needed over a longer period. (i)

State two foods that are a good source of monosaccharides.

1. Honey

2. Milk (1)

(ii)

State two foods that are a good source of polysaccharides. polysaccharides.

1. Bread

2. Pasta (1) (Total 5 marks)

8.

(a)

Describe how the ileum uses active transport in the absorption of food. .......................................................................... ....................................... ................................................................... ........................................................... ........................... .......................................................................... ....................................... ................................................................... ........................................................... ........................... .......................................................................... ....................................... ................................................................... ........................................................... ........................... .......................................................................... .......................................... ................................................................ ........................................................... ........................... .......................................................................... ....................................... ................................................................... ........................................................... ........................... .......................................................................... ....................................... ................................................................... ........................................................... ........................... .......................................................................... ....................................... ................................................................... ........................................................... ........................... (3)

(b)

List two substances substances resulting from the breakdown of haemoglobin h aemoglobin in the liver. .......................................................................... ....................................... ................................................................... ........................................................... ........................... (1) (Total 4 marks)

9.

Researchers extracted an enzyme from the human digestive system and tested its activity at different pH values on proteins extracted from the blood of cows. The results are shown in the

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graph below.

Enzyme activity

1 2 3 4 pH a)

Deduce from where in the human digestive digesti ve system this enzyme was extracted.

[1]

Stomach  b)

Outline the need need for enzymes enzymes in the digestive digestive system. system.

[2]

Enzymes are necessary in digestion because they act as catal ysts for the hydrolysis of complex organic molecules into their monomers. They do this by lowering the activation energy required for hydrolysis to start. c)

State one function of the large intestine.

[1]

short-term waste storage d)

Explain how the structure of the villus is adapted adapted for absorption.

[3]

The villus is shaped like many fingers, increasing surface area and t herefore maximising maximising absorption. It also has a direct link to the t he blood supply via capillaries, making making absorption and transportation quicker and easier. (4) (Total 7 marks)

10.

HL

Enzymes are used by living organisms to catalyse reactions. Some of these reactions occur in the cytoplasm of cells. Other reactions take place outside cells, for example the digestion of foods in the human gut. (a)

State the name used by biochemists for the chains chains and cycles of reactions reactions that occur inside cells. Cell metabolism (1)

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(b)

Enzymes Enzymes of digestion in humans are secreted secreted by glands. glands. They have a pH optimum which allows them to work efficiently in the part of the gut into which they are secreted. secreted. (i)

In the table below, identify the missing enzyme, enzyme, the two glands, and the pH optimum

Name of enzyme

Gland secreting the enzyme

Substrate

Products

pH optimum

amylase

Salivary glands

starch

maltose

7

Pancreatic lipase

Pancreas

triglycerides

fatty acids and glycerol

7 (4)

(ii)

Outline the effect effect of pH values values above above and below below the the optimum optimum on enzyme enzyme structure.

Enzymes Enzymes become uncoiled, and, as they lost their shape, lose their ability to metabolize their specific substrates. (2)

(c)

Enzymes Enzymes that work inside cells are sometimes sometimes affected by non-competitive inhibitors. Explain how a non-competitive inhibitor affects the activity of an enzyme. enzyme. A non-competitive non-competitive inhibitor may become attached and block an enzyme’s active site. This prevents substrates from attaching to the enzyme to be broken down, stopping enzyme activity. (3) (Total 10 marks)

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11.

Osteoporosis is a major health problem for many many post-menopausal women. As the the ovaries reduce their secretion of estrogen, calcium is gradually lost from bones, weakening them and increasing the chance of fractures. To test whether diet influences the rate of calcium loss, ovaries were removed removed from groups of female rats and the rats were then either fed a control diet or the same diet with one gram of a supplementary supplementary food per day. The rate at which the rats excreted calcium was measured. The ratio of calcium loss between the control rats and the rats

 

loss with supplementary food 

 

loss in controlrats

that were given a supplementary food was calculated.  Ratio 

 .  

The results are shown in the graph below. 1.2 1.0 0.8 Calcium loss ratio

0.6 0.4 0.2 0.0

  e   g     b  a    b   c  a

  g    e  g 

   i  c    l   a  r   g 

  y    l  e   s   r   p  a

  t   e  a   m

  n    i  o   o  n

  o   n    k   t  o    l    i   e  a   m  a  t   t  a    b   m   o    p   y   t  o   e  d   s  o   m    i  m    k   s

Supplementary food [Source: Muhlbauer and Li, Nature Li,  Nature,, 1999, 401, pages 343 – 344] 344]

(a)

(i)

Identify which supplementary supplementary food was most effective in reducing calcium loss. Parsley (1)

(ii)

Identify which supplementary supplementary food was least effective in reducing calcium loss. Egg (1)

(b)

Among the ten foods shown in the graph, seven are plant products (vegetables) (vegetables) and and three three are animal products. Discuss whether the plant or the animal products were more effective at reducing calcium loss. Egg and meat, both animal product, showed a higher r atio of calcium loss than most of the plants, such as parsley, garlic and cabbage. Skimmed Skimmed milk, however, has a lower ratio, lower than soy-bean and potato supplements. supplements. On the whole, however, most of the plant products have a ratio lower than that of meat products, at least 0.1 units lower. (3)

(c)

Suggest a trial, based based on the results shown in the graph, graph, that could could be done to try to reduce osteoporosis in humans. Run a trial with women in the menopause stage, with a control group and several groups taking different supplements. Examples of supplements could include (3) (Total 8 marks)

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