Deck 22: Introduction to Seed Plants: Gymnosperms

Question 1

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

Answer 1

Plants are the living system that works on growth through seeds. Every element of plant body is specifically structured and created as per its requirement to survive and to overcome the habitat and climate changes that occur.
Understanding this element it can be seen that some plants have broad leaves where others have short or needle like leaves. For example Ginkgo and cycads have broad leaves whereas; pine tree leaves are needle shaped. It's not just the structure for appearance but has significance for survival and climatic changes the plant lives in. Cornifers like pine are developed in extreme cold and stormy climatic areas, the structure of leaves are needle shaped so as to retain more water and tolerate more wind during storm and prevent the tree to fall. The needle like leaves prevent snow accumulation on the trees and helps in survival in extreme cold climatic conditions. On other hand Ginkgo and cycads are advanced conifers that have broad and overhanging leaves, this is because these plants are mainly found in temporal region and have to tolerate the cold and retain water. As these plants mostly face moist and humid climate the variation in their leaves is found to adjust the climatic changes.
Therefore, there are significant differences between the leaf structures of these plants.

Question 2

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

Answer 2

Gymnosperm is a word which is derived from two Greek words that is gymnos which means naked and sperma which means seed. So the word gymnosperm means the seeds with exposed nature.
In gymnosperms, the seeds are naked and produced on the sporophylls surface and are not enclosed within a fruit.
The sporophylls of sporophyte that bear seeds are spirally arranged in form of seed cones called strobili and these develop along with the pollen cones strobili which bear pollen and produce pollen grains.
In gymnosperms, the female gametophyte is produced inside the ovule and nucellus is present which is a fleshy tissue enclosed within one or more outer tissue layers called integument. After fertilization, this integument develops into a seed coat and the embryo development takes place. The cell number of gametophytes are reduced in cell number and these develop within the structures of sporophyte.

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 evolution was marked by differentiation of the two main classes of plant and animals kingdoms. This differentiation was done on basis of the reproduction cycle and structures the species of both the kingdom possessed.
If no differentiation was made during evolution into plant and animal kingdom, the human can be well included into gametophytes, as human beings are living organism that has multicellular structures. They form gametes with help of mitosis and reproduce. As seen many bisexual gametophytes act in similar way that have a female ovary and produce ovum as well as male testis and produce sperms for reproduction.
Therefore, human class can be seen as a similar class of gametophytes in plants as they reproduce through gametes.

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 nonnative 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 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.