The purple flower must have the P-allele because purple is dominant. We do not know what the other allele is – P or p. Let us suppose the other allele is P.

Up crossed with Up (true-bred white) Gametes through meiosis: P crosses with p Fl-generation is all Up, all purple If the outcome of our cross is purple flowers, we know that the purple flower was also true-bred. Let us look at the other option, where the purple flower is a heterozygous – P- generation: Up (heterozygous) crossed with Up (true-bred white) Gametes through meiosis: P and p crossed with p and p p UpPhenotype: 2 purple to 2 white If the outcome of our cross is 2 purple flowers to 2 white flowers, know that the purple flower Was a heterozygous. Question 13.

10: Describe the structure and function of ribosome. Answer: Ribosome are made of types of subunits – large and small subunits. The ribosomal subunits are made up of proteins and RNA molecules are called ribosomal RNA, or RNA. (10) 5 The ribosomal subunits are made in the nucleolus. The subunits are then transported via the nuclear pores to the cytoplasm.

Approximately two-thirds of the mass of a ribosome is RNA.The ribosome of eukaryote are slightly larger than those of prokaryote. Ribosome play a role in the formation of polypeptides. Question 14. 8: Define predation, herbivore and parasitism. Predation: The interaction in which a predator eats another animal.

Herbivore: The interaction in which a herbivore eats a plant. Parasitism : A symbiotic relationship in which the parasite benefits at the expense of the host. Question 15. 1: Distinguish between authors and waterproofs.

Authors are organisms that use CO as a source of carbon and light energy to manufacture their own food.Authors are also known as primary producers of the ecosystem. Waterproofs are organisms that use organic compounds as a source of carbon. Waterproofs depend on other organisms for food.

Question 15. 8: Write short notes on the greenhouse effect. CO, water vapor, sulfur dioxide and other greenhouse gases in the atmosphere intercept and absorb radiant energy emitted by the earth and reflect it back towards the earth.

This process causes some of the solar energy to be retained. The greenhouse effect is believed to have contributed o the present global warming. Question 16. 4: Explain how edges and corridors can strongly influence landscape biodiversity.

Boundaries (edges) between ecosystems and along prominent features within ecosystems have unique sets of physical conditions and communities of species.