This homework solution contains answers to questions related to plant reproduction (generative nucleus, tube nucleus, double fertilization), biomolecules (chitin, lignin), speciation (allopatric speci

Here are the answers to the questions:

5. a) Name the part labelled M and N.
M: Generative nucleus
N: Tube nucleus

b) Explain the roles of the part labelled M.
The generative nucleus (M) divides to form two male gametes. One male gamete fuses with the ovum to form the zygote, and the other fuses with the polar nuclei to form the endosperm, leading to double fertilization.

6. Name the polysaccharides found in the following structures:

• Exoskeleton: Chitin
• Xylem vessels: Lignin

7. Explain how geographical distribution resulted in the formation of new species.
Geographical distribution leads to allopatric speciation. When a population is separated by a geographical barrier (e.g., mountains, rivers), gene flow between the isolated populations is prevented. Over time, each population experiences different selective pressures, mutations, and genetic drift, leading to genetic divergence. Eventually, the populations become reproductively isolated, meaning they can no longer interbreed, thus forming new species.

8. The diagram below shows the transverse section of a young stem.
Identify the parts labelled A, B, C, D, and E.
A: Phloem
B: Endodermis
C: Cortex
D: Pith
E: Xylem