Correct Answer: D. Stem cuttings

Correct Answer: C. use and disuse

Correct Answer: D. dorso-ventrally flattened body

Correct Answer: C) absence of large vacuoles

Explanation

This Biology question is asking about the characteristics of an animal cell. The options given are A) presence of chloroplasts, B) possession of a cellulose cell wall, C) absence of large vacuoles (which is the correct answer), and D) presence of large vacuoles. An animal cell is a type of eukaryotic cell that makes up the tissues and organs of animals. Unlike plant cells, animal cells do not have chloroplasts, which are organelles responsible for photosynthesis. Therefore, option A is incorrect. Cellulose is a type of carbohydrate that provides structure and support to plant cells. However, animal cells do not have a cellulose cell wall. Instead, they have a flexible cell membrane that allows for movement and communication between cells. Therefore, option B is also incorrect. Vacuoles are membrane-bound organelles found in cells that store waste, nutrients, and other substances. While animal cells do have vacuoles, they are generally smaller in size and not as prominent as the large central vacuole found in plant cells. Therefore, option D is incorrect, and option C, absence of large vacuoles, is the correct answer. Understanding the differences between plant and animal cells is important in Biology as it helps to differentiate the characteristics of these two types of cells and their functions in living organisms.

Correct Answer: D. thyroxin

Correct Answer: D) b-d-a-c

Explanation

The correct sequence of steps in protein digestion is option D: b- d-a-c, which represents protein ? peptones ? polypeptides ? amino acids. Protein digestion is a process that breaks down dietary proteins into smaller components, which can be absorbed and utilized by the body. The process occurs in the following sequence: Protein: These are large complex molecules made up of long chains of amino acids. They are the starting point of protein digestion. Peptones: Proteins are first broken down into smaller fragments called peptones by the action of enzymes like pepsin in the stomach. Peptones are intermediate products in the process of protein digestion. Polypeptides: Peptones are further broken down into shorter chains of amino acids called polypeptides by the action of enzymes like trypsin and chymotrypsin in the small intestine. Amino acids: Finally, polypeptides are broken down into individual amino acids by the action of enzymes like carboxypeptidase and aminopeptidase in the small intestine. Amino acids are the end products of protein digestion and can be absorbed by the body for various functions like building and repairing tissues. In summary, protein digestion involves breaking down complex protein molecules into smaller components, starting with peptones, then polypeptides, and finally into individual amino acids that can be absorbed by the body.

Correct Answer: D. Chlamydomonas

Correct Answer: C. homologous structures

Explanation

A bat's wing and a bird's wing are analogous structures, as the development of these structures does not share an evolutionary history. The common ancestor of bats and birds did not have wings, therefore these traits arose independently. Therefore, they are not homologous, but represent convergent evolution, as similar traits arose from different lineages due to environmental pressures.

Explanation

(a)(i) Habitat

The natural dwelling place of an organism. OR A place/locality where an organism lives successfully

(ii) Role of a decomposer in an ecosystem

Decomposers are organism which bring about the decay of dead parts/whole of plants/animals; to produce manure/humus; they release nutrients in them into the soil; which are absorbed by roots of plants; and are used to build up new plant tissues; they thus help in nutrient recycling; also release offensive gases/odour which pollute the air.

(b) Energy flow in a freshwater habitat;

Common aquatic plants/Pistia/Spirogyra/any correctly named aquatic plant; using energy from the sun; photosynthesize/produce food; the food is eaten by primary consumers/animals; small aqautic animals would be eaten by bigger aquatic animals/secondary consumers; tertiary consumer/a much bigger fish/any correctly named fish will feed on secondary consumer, in the process of feeding energy flows from one trophic level to another; decreases progressively; dead animals/plants decompose; energy is lost.

(c)(i) Harmful effects of microorganisms to plants

1. They cause diseases
2. They can cause undesirable qualities in plants/plant product
3. They cause spoilage
4. Reduction in yield

(ii) Beneficial effects of micro organisms to humans

• Bacteria/decomposers help to decay/decompose dead organisms to release nutrients
• Bacteria is used in cleaning/mopping up oil spillage
• Used in the fermentation of foods/cocoa beans/garri/locust beans/kenkey production
• Used to make vinegar
• Used in making alcoholic beverages/wine/beer/spirit
• Used in making some antibiotics/penicillin
• Used in the manufacture of insulin
• Used in making cheese/yoghurt/bread/Single Cell Proteins
• Used in making flax/tanning of leather;

Explanation

(a)(i) Hydrosphere is the aquatic portion of the biosphere or life supporting living world or earth.

(ii) Examples of hydrosphere are: Lake, Pools, Spring, Oceans, Ponds, Oasis, Rivers, Streams, Manny.

(b)(i) The first law of thermodynamics states that energy can neither be created nor destroyed. The second law of thermodynamics states that in any conversion of energy from one state to another, there is always a decrease in the amount of useful energy.

(ii) Using the second law of thermodynamics, the energy flow across trophic levels can be explained as follows:

• The transfer of energy between trophic levels is not 100%. That means it is not completely transferred.
• Successive levels have less of useful energy and support fewer organisms.
• Primary producers/plants have the highest amount of energy and when herbivores feed on plants, the energy level is reduced.
• When carnivores consume the herbivores the energy level is further reduced.

(c) (i) Local biotic communities and the state each is found in Nigeria are:

(ii) Factors affecting marine organisms are: Temperature, Salinity, Pressure, Turbidity/light penetration, Dissolved oxygen, Density of sea water, PH/hydrogen ion concentration, Waves /up-welling of water, Current and Tides.

(iii) Adaptive features of sea weeds are;

(1) Possession of chloroplast/photosynthesis

(2) Absence of lignified tissue which makes them flexible and able to withstand wave actions

(3) Possession of hold fast for firm attachment to substratum or rocky surface

(4) Body covered with mucilage to reduce desiccation during low tide or on exposure

(5) Possession of air bladders for buoyancy.