Chapter 3 Solutions — Plant Kingdom

Algae are classified primarily on the basis of the following criteria:

1. Type of pigments present: Chlorophyceae (green algae) contain chlorophyll a and b; Phaeophyceae (brown algae) contain chlorophyll a, c, carotenoids and fucoxanthin (a xanthophyll); Rhodophyceae (red algae) contain chlorophyll a, d and phycoerythrin.

2. Nature of stored food: Green algae store starch; brown algae store laminarin or mannitol; red algae store floridean starch (similar to amylopectin and glycogen).

3. Cell wall composition: Green algae have a cellulose cell wall; brown algae have cellulose covered with algin; red algae have cellulose, pectin and polysulphate esters.

4. Flagellar number, position and type of insertion: Green algae have 2-8 equal flagella with apical insertion; brown algae have 2 unequal flagella with lateral insertion; red algae are non-motile (flagella absent).

5. Habitat: Though most algae are aquatic, the three classes differ in the proportion of freshwater vs marine forms.

1. Protonemal cell of a moss: Haploid (n) — the protonema is part of the gametophyte generation.

2. Primary endosperm nucleus in dicot: Triploid (3n) — formed by fusion of one male gamete (n) with two polar nuclei (n + n), giving 3n.

3. Leaf cell of a moss: Haploid (n) — the leafy shoot is part of the gametophyte; all its cells are haploid.

4. Prothallus cell of a fern: Haploid (n) — the prothallus is the gametophyte of pteridophytes.

5. Gemma cell in Marchantia: Haploid (n) — gemmae are produced by the gametophyte and are thus haploid.

6. Meristem cell of monocot: Diploid (2n) — the plant body of angiosperms (sporophyte) is diploid.

7. Ovum of a liverwort: Haploid (n) — the egg (ovum) is produced by the gametophyte and is a haploid gamete.

8. Zygote of a fern: Diploid (2n) — formed by fusion of a haploid male gamete (n) and a haploid egg (n).