Question

1. Look at the pine life cycle and compare it to the life cycles of the seedless vascular plants. Emphasize the main differences between the life cycles.

2. Observe the pine microsporangiate strobili (male cones).

a. Do you think the male cones are persistent? Why?

b. How is this trait related to the type of fertilization utilized by pines?

3. Now look at a slide of pine pollen.

a. What structures do they have that might help their dispersal?

4. Check out the slide of the male cone.

a. What types of cells give rise to the pollen grains?

5. Now observe the megasporangiate strobili (female cones) on display and draw two of them.

a. How do they differ in size and structure from the male cones?

b. Look at the ovuliferous scales. What evidence is there that seeds developed on these scales? It takes almost two years for the seeds of some pine species to ripen in the cone.

6. View the slide of the conifer seed.

a. What is the ploidy of the embryo, seed coat, and food tissue?

7. Now observe the seeds of a Podocarpus.

a. Which part of the seed is fleshy?

Answer 1

2a. No male cones are not persistent because they do not give rise to zygote and therefore they are not related to the nutrition of zygote.

2b. Pinus show internal fertilization inside the female cone and there for male cone need not be persistent.

3a. Pollens have wings due to which they can float in air. They show wind pollination.

4a. Microspore mother cells present in microsporangium

5a. Female cones are bigger and less compact than male cone.

5b. Some of the seeds were found attached to the ovuliferous scales giving evidence that they were borne on these scales.

6a. Embryo is 2n, seed coat is n and food is 3n.

7a. Endosperm

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