Lab Quiz 3 (Lab 8: Gymnosperms)

Question 1

(cycads)
Why are their leaves stiff?
Why would evergreen plants have stiff leaves?

Answer 1

Their leaves are stiff because they have lignin in their cell walls.
Evergreens have stiff leaves so that the leaf tissues can last a long time. They need to prevent/protect the tissues from damage and cavitation.

Question 2

(cycads)

How do the leaves differ among Cycas, Zamia, and Encephalartos?

Answer 2

Cycas have thin leaflets with a terminal spine, Zamia have broader leaflets with rounded ends and Encephalartos have spiny margins.

Question 3

(cones of cycads)

How do the male and female cones differ in their persistence and size?

Answer 3

Male cones are thinner, smaller and woody and persistent. Female cones are wider, larger and ephemeral

Question 4

(cones of cycads)
Are any of the cones or seeds colorful?
How might the colors influence their dispersal?

Answer 4

Yes, both female cones and seeds are colorful and some male cones are too.
Colors attract animals and birds to disperse pollen and seeds.

Question 5

(cones of cycads)
Unlike most other groups of gymnosperms, cycad species are often pollinated by animals. What advantages would there be for cycads to be animal pollinated considering the fact that most occur in tropical forests?

Answer 5

Tropical forests have dense vegetation, and if they relied on wind pollination, the pollen would get blocked before it could reach a female of the same species. Pollen can reach females of the same species when it is carried on the body of an animal, giving an advantage to this type of pollination strategy.

Question 6

(observe seeds)

What is interesting about their form?

Answer 6

They look fleshy/look like fruit.

Question 7

(observe seeds)

What is the fleshy portion of the ripe seed?

Answer 7

The seed coat

Question 8

(observe seeds)

Look at the picture of an opened Ginkgo seed. What is the ploidy of the embryo and the food tissue?

Answer 8

The embryo is 2n and the food tissue is 1n.

Question 9

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

Answer 9

The main differences is that the sporophyte is dominant and the gametophyte is housed on and depends completely on the sporophyte. The evolution of pollen and of seeds also are distinct differences.

Question 10

(pine microsporangiate strobili) =

Answer 10

male cones

Question 11

(pine microsporangiate strobili)

Are they ephemeral or long lasting?

Answer 11

They are ephemeral (short-lived)

Question 12

(pine microsporangiate strobili)

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

Answer 12

Pines use wind pollination to accomplish fertilization. The wind blows the pollen away quickly when it is mature, and once the pollen is gone there is no longer a need for the cone to remain.
It is more energy efficient to make a cone that is small and ephemeral.

Question 13

(pine pollen)

What structures do they have that might help their disperse?

Answer 13

Banners help them float on the air and disperse further

Question 14

(male cones’ microsporophylls and microsporangium)

What types of cells give rise to the pollen grains?

Answer 14

Microspores (microspore mother cells) give rise to the pollen grains

Question 15

megasporangiate strobili =

Answer 15

(female cones)

Question 16

(megasporangiate strobili)

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

Answer 16

The female cones are much larger, woody and persistent, while the males are small and ephemeral.

Question 17

(megasporangiate strobili)

Look at the ovuliferous scales. What evidence is there that seeds developed on these scales?

Answer 17

It takes almost two years for the seeds of some pine species to ripen in the cone.
There are two grooves/ indentations/ depressions/ discolored areas where the seeds once developed.

Question 18

(seeds of a Podocarpus)

Which part of the seed is fleshy?

Answer 18

The outer layer of the seed coat is fleshy

Question 19

(welwitschia)

How many leaves does it produce during its lifetime?

Answer 19

It produces only 2 leaves that continuously grow throughout its lifetime.

Question 20

(welwitschia)

What is interesting about the base of the plant?

Answer 20

The base of Welwitchia is woody with a basal meristem.

Question 21

(ephedra)
Look at a section of the wood using the microscope, draw it and label the vessels and tracheids.
What other gymnosperms have vessels?

Answer 21

Only the gymnosperms in the Gnetales group have vessels

Question 22

(ephedra)
The male and female cones are on display.
How do their cones differ from other conifers?

Answer 22

They are both very small;

the male cones resemble flowers and the female cones bear only one seed.

Question 23

(gnetum)

How does the stem and leaf morphology of this genus differ from those of Welwitschia and Ephedra?

Answer 23

Gnetum is broad-leaved, and its stems and leaves make it look more like angiosperms.

Question 24

Why are pollen tubes important?

Answer 24

Pollen tubes facilitate the movement of the sperm down into the ovule.

Question 25

Are the sperm of pines flagellated?

Answer 25

no