a. Define two factors which control neoteny.
i) Thyroid hormones regulate neoteny.
ii) Pituitary gland hormone (TSH) regulates the activity of the thyroid gland and as a result control neoteny.
b. Give two examples of neoteny.
Salamander species axolotl and the a north American amphibian rough skinned newt show neoteny.
c. What is an electric organ?
In biology, the electric organ is a muscular organ (more accurately, derived from muscle) common to all electric fish used for the purposes of creating an electric field; a behavior used for navigation, communication and also sometimes for the incapacitation of prey.
d The female Gastric-brooding Frogs (genus Rheobatrachus) from Australia, swallows its tadpoles, which then develop in the stomach.
(x2 marks each)
a What is parental care?
Parental care may be defined as all of the help that a parent gives to its offspring, including (in some cases) feeding, sheltering, and protecting them from predators.
b. What are the immediate causes of bird migration?
The immediate causes of bird migration are as follows:
a) Food: The change of seasons causes a change in food supply, causing birds to move to an area with a more plentiful food supply.
b) Reproduction: Birds also migrate to a specific area to breed and raise their young.
c. What is electric organ discharge (EOD)?
Electric organ discharge (EOD) is the electric discharge generated by the organs of animals including electric fish. In some cases the electric discharge is strong and is used for protection from predators; in other cases it is weak and it is used for navigation and communication.