The code in pairs of nucleotides

 The DNA code is read in groups of three nucleotides called codons. Explain why reading the code in pairs of nucleotides is not sufficient. [K/3marks] 3. How does the fact that DNA Replicates semi-conservatively decrease the possibility of errors made during DNA replication? [A/3marks] Unit 4 – Homeostasis I Define and give an example of homeostasis; negative feedback and positive feedback loops [K/3marks] 2.

Describe how the endocrine and the nervous systems interact to compensate for temporary fluctuations in the body’s internal environment (for example, in situations of stress) [A /3marks] 3. Why the Pituitary gland is known as the master gland of our body. Explain it with one example. [Comm/3 marks] Unit 5 – Population Dynamics 1. Give the conclusions of Malthus’s theory. [K/3 marks] 2. Explain factors as abiotic or biotic limiting factors and describe and identify carrying capacity [C/3marks] 3. Define population density. A/3 marks]