Theory question 105
Sense OrgansSection B
(a)(i) What are sense organs?
(ii) Name three sense organs that respond to the stimulus of chemicals.
(b) List three animals each that exhibit the following courtship behaviours. (i) territoriality (ii) pairing
(c)(i) State one similarity between the eggs of toads and the eggs of birds.
(ii) State three differences between the eggs of toads and the eggs of birds.
(d) Complete the table below by listing four organisms involved in the nitrogen cycle and state one role each of the organisms.
(e) Complete the table below by naming two types of heterotrophic modes of nutrition in animals and give two examples each of the organisms that carry out the modes of nutrition.
Table columns: Two modes of heterotrophic nutrition | Two examples of organisms that carry out mode of nutrition
Show the model answer
(a)(i) Organs containing groups of receptor cells that detect stimuli (changes) in the surroundings and send impulses to the nervous system.
(ii) Tongue (taste buds); nose (olfactory cells); in insects, the antennae (chemoreceptors). Accept chemoreceptors in the carotid body.
(b)(i) Territoriality, any three: agama lizard, male tilapia, dog, lion, robin/many birds, chimpanzee.
(ii) Pairing, any three: termites, pigeon/domestic fowl/duck, toad, gibbon, human.
(c)(i) Both contain yolk (food for the embryo) / both develop into an embryo / both have a vitelline membrane.
(ii) Any three: toad eggs have a jelly coat, bird eggs a hard calcareous shell; toad eggs are small, bird eggs large; toad eggs laid in many numbers in strings, bird eggs laid singly; toad eggs fertilised externally in water, bird eggs internally; toad eggs lack an air space and chalaza, bird eggs have them; toad eggs are laid in water, bird eggs on land.
(d) Any four: Rhizobium/Azotobacter - fix atmospheric nitrogen into nitrogen compounds; putrefying bacteria and fungi - break down dead bodies to ammonium compounds; Nitrosomonas - change ammonium compounds to nitrites; Nitrobacter - change nitrites to nitrates; Pseudomonas (denitrifying bacteria) - change nitrates back to nitrogen gas; green plants - absorb nitrates to make proteins; animals - eat plant protein and return nitrogen in excreta and dead bodies.
(e) Holozoic - e.g. man, dog, goat, Amoeba; Parasitic - e.g. tapeworm, tick, louse; (also accept saprophytic - e.g. some protozoa; or symbiotic).
Lightning and fertilisers are not organisms, so do not list them in (d).