Correct Answer: C. population

Correct Answer: A) capturing prey

Explanation

Cnidarians are aquatic animals that include jellyfish, corals, and sea anemones. Nematocysts are specialized cells that cnidarians use to capture prey, defend themselves, and compete for resources. These cells contain a coiled, barbed thread that can be rapidly ejected to entangle prey or fend off predators. Therefore, the correct answer to the question is option A: capturing prey. It is worth noting that cnidarians have a simple nervous system that allows them to sense their environment and respond to stimuli. For example, they can detect light, chemicals, and vibrations in the water. However, nematocysts are not used for sensing chemicals (option D) or for gas exchange (option C). Courtship (option B) is also not applicable to cnidarians, as they reproduce asexually or sexually by releasing gametes into the water. In conclusion, cnidarians use their nematocysts primarily for capturing prey, which is an essential aspect of their survival and ecological role in aquatic ecosystems.

Explanation

(b)(i)Two main functions of the ear are:

Hearing and maintenance of balance.

(ii) The mechanism involved in hearing are;

1. The pinna; collects sound waves in the air, concentrates them and passes them on through the external auditor) canal or meatus.
2. The waves; cause the tympanic membrane or ear drum to vibrate. The vibrations are passed on to the ear ossicles (mallens, inclus and stapes) which amplify them.
3. The round oval window;fenestral oval is rotunda also vibrates, passing the waves into the cavity of the inner ear, cochlea, where the perilymph vibrates, transmits the waves in the cochlea which also causes the endolymph of the cochlea to vibrate. The vibrations are then transmitted across the organ of cot or sensory nerve cell or basilar membrane.
4. The impulses;are set up and they stimulate the auditory nerve cells which then transmit the impulses to the brain, for interpretation.

The mechanisms involved in the maintenance of balancing are as follows:

Head movement in any direction affects the fluid or endolymphy, in the corresponding semicircular canals, which are at right angles to each other. This forces the sensory cells, gelatinous copula in the ampulla, to set up impulses through the auditory nerve to the brain and intern, for interpretation. The brain relays the impulses to the body muscles, for balancing/ determine the position of the body.

Correct Answer: B. are used in the site of production

Explanation

(a) A balanced diet contains all the six classes of food which are carbohydrates, protein, fat, vitamins, water and mineral salts.

(I) Examples of the classes of food

(c)(i) Functions of protein in human are:

(i) It is useful for growth and formation of new cell.

(ii) Protein is used for repair of worn out tissues.

(iii) It functions in the formation of Hormones.

(iv) It yields certain amount of energy.

(v) It is also useful for formation of enzymes.

(ii) A child with protein deficiency will have the. following features:

(i) The child will have retarded growth.

(ii) Loss of weight is also common to such child

(iii) He will develop swollen legs, oedema and swollen feet

(iv) He develops cracked and split skin

(v) The child will have distended and swollen stomach resulted to kwashiorkor.

(vi) He develops pale body.

(vii) There is also a change in the hair; the hair becomes reddish brown

(viii) The child also develops thin and tiny legs

(ix) The child will have distended and smoker stomach resulted to kwashiorkor.

(d)(i) One organelle in a living cell that produces enzymes is Ribosomes.

(ii) Enzymes that act on proteins are:

(i) Pepsin

(ii) Trypsin

(iii) Rennin.

Correct Answer: C. Secreting irritating fluid

Correct Answer: A. There is an excess of potassium ions inside the axon and an excess of sodium ions outside

Correct Answer: A. As random genetic mutations arise within an organism's genetic code, those that best allow an organism to survive and reproduce will be preserved and passed on to future generations.

Explanation

Darwinian evolution is often summarized as survival of the fittest but this does not necessarily mean fit in terms of being strong or athletic. Fitness in Darwinian terms describes the ability to survive to reproductive age and pass on genetic material to offspring. Random genetic mutations that contribute to this ability will be preserved and passed on to future generations. Darwinian fitness is typically measured by number of offspring that survive to reproductive age. While a fit organism will survive long enough to reproduce, life span alone doesn't define Darwinian fitness, nor does speed of evolution. The concept of passing on traits acquired during the lifetime is consistent with Lamarckian evolution, which is less commonly accepted than Darwin's principles.

Correct Answer: C. Coal

Correct Answer: D. manufacture food for animals