Deck 22: Introduction to Seed Plants: Gymnosperms

Question 1

Ginkgo and cycads have broad leaves, whereas those of pines are needle-like. Can you suggest any significance of this difference in terms of the climates and habitats involved?

Answer 1

Ginkgo and cycads have broad leaves, where pines are needle like. The significance of the difference is due to varying climates and habits.
In Ginkgo leaves are spirally arranged for maximum capturing of light. Whereas pines have needle like leaves which are adopted to conserve water by reducing the process of evaporation. This is due to successful variation in temperature and cold climates.
Needle like leaves contain sunken stomata with thick epidermis to resist the excessive heat. The leaves are often green because they absorb maximum amount of energy at higher altitudes due to weak sunshine.

Question 2

What is a gymnosperm? How is it distinguished from other major groups of plants?

Answer 2

Gymnosperm refers to the plants with exposed seeds which are produced on the surface of sporophylls; instead of being enclosed within a fruit like flowering plants.
They are distinguished from other major groups of plants by producing seeds (female) on the surface of the sporophylls of sporophyte which are arranged in strobili. The strobili also produce pollen grains (male).
The female gametophyte is present inside an ovule which is surrounded by integument to form seed coat after fertilization. The gymnosperm sporophytes are trees and shrubs where some of the species are vines.

Question 3

If no distinction were made at the level of kingdom between plants and animals, what would be the equivalent, if any, of sporophyte and gametophyte in humans?

Answer 3

The sporophyte and gametophyte differs among different plants which has alteration of generation. The sporophyte is less developed in liverworts, mosses and hornworts. In flowering plants there is reduction of gametophyte.
If there is no distinction between the level of kingdom between the plants and animals it would trend to lot of confusion in placing the plant or animal. Animals differ differently compared to plants. If there is no classification; the mature animal that is diploid is equivalent to sporophyte. Animal produces gametes directly by meiosis. No haploid spores are produced so gametophyte is haploid. Hence there is no alteration between diploid and haploid form.

Question 4

What is the difference between a seed and a spore?

Question 5

Both bristlecone pines and redwoods can live to be thousands of years old. What do you suppose makes this possible?

Question 6

How are the leaves of pines different from those of broadleaf flowering plants?

Question 7

Most of the old-growth stands of conifers in North America are now gone, and others will be gone soon. Much of what has been harvested is being replaced with new growth, sometimes with hybrids and non-native plants. Our forests are essential to our economy as we know it. If you had the power to change the way we manage and exploit our natural forest resources, what would you do differently, assuming you did not want to damage the economy?

Question 8

What is a resin canal, and what is its function? Where are resin canals found?

Question 9

If money were no object and you wished to landscape your yard primarily with gymnosperms, realistically, what would you include, taking into account your particular geographical area? Why?

Question 10

How do pines differ in their reproduction from ground pines and ferns?

Question 11

How do pollen grains differ from spores or sperms?

Question 12

Which conifers discussed in this chapter do not have woody seed cones?

Question 13

If you had samples of leaves of a pine, Ginkgo , a cycad, a joint fir, and Welwitschia all together, indicate how you could tell them apart by constructing a key.

Question 14

What parts of a pine are considered edible?

Question 15

What is resin? Discuss some of its uses, past and present.