Biology CSEC Notes

2.3 Importance of soil in providing water, mineral nutrients and oxygen; 

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Oxygen: the spaces among soil particles contain air that provides oxygen, which living cells use to break down sugars and release the energy needed to live and grow. Water: the spaces among soil particles also contain water, which moves upward through plants. This water cools plants as it evaporates off the leaves and other tissues; carries essential nutrients into plants; helps maintain cell size so that plants don’t wilt; and serves as a raw material for photosynthesis Nutrients: soil supplies nutrients, and also holds the nutrients that we add in the form of fertilizer.

Importance of air in providing various raw materials: oxygen, carbon dioxide, nitrogen. 

Plants absorb CO2 from the air and by the action of light which is conducted through chlorophyll will free oxygen in air which facilitates for respiration in animals and humans.

Importance of light and temperature. 

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Light is the main source of energy for organisms. Light has an important part to play in the life of most plants as it is utilized by them for the process of photosynthesis where light energy is converted into chemical energy and into complex organic substances important for growth, flowering and germination. All plants and animals are adapted to survive between a minimum and maximum range of temperature. The earth’s surface has different temperatures in different zones and while some animals and plants can bear extreme heat or extreme cold, some survive well in moderate temperature ranges.

3.2 Terrestrial food chain: Carrots - rabbit - snake – eagle Aquatic food chain: Plankton - shrimp - herring – cat

3.3 Herbivore

Terrestrial habitat horse

Aquatic habitat

Carnivore Omnivore

tiger bear

sharks

3.4 3.5

3.6 Role of decomposers - Decomposers are nature's recyclers as they break down the organic matter found in the dead bodies of plants and animals. The term 'organic matter' refers to the matter that comes from living organisms. Bacteria and fungi produce chemicals, called enzymes that digest dead material. The digested material then provides a food source for other organisms in the soil. This makes the role of a decomposer extremely important in an ecosystem. Without them, organic matter would pile up on the ground and plants would not receive the required nutrients necessary for their survival. The decomposing process greatly increases the nutrient-load of an ecosystem which allows for greater biodiversity. 3.7   

Mutualism: Egret and cow, Termite and sea anemone, leguminous plants and nitrogen fixing bacteria Commensalism – barnacle and large sea animals, epiphytes and trees, remora and shark Parasitism – lice and human

4.1 Energy is transferred along food chains from one stage to the next. But not all of the energy available to organisms at one stage can be absorbed by organisms at the next one. The amount of available energy decreases from one stage to the next. Some of the available energy goes into growth and the production of offspring. This energy becomes available to the next stage, but most of the available energy is used up in other ways:  

energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings energy is lost in waste materials, such as faeces