Seed Plants

Question 1

How have the seeds contributed to the evolutionary success of seed plants?

Answer 1

• It protects and provides food for embryo
• Allows the “clock to be stopped” to survive harsh periods before germinating
• First seed plants did not produce fruits. Development of fruits enhanced dispersal.

Question 2

Why are seed plants described as heterosporous?

Answer 2

Because they have two types spores: male and female.

Question 3

What “mega” and “micro” refer to?

Answer 3

Mega: female reproductive stages (female spores are larger)
Micro: male reproductive stage

Question 4

Where are the reproductive structures located?

Answer 4

They are in the cone/ strobilus for gymnosperms or flower for angiosperms. Most parts of the cone or flower are sporophytes.

Question 5

What is the dominant stage in seed plants?

Answer 5

It is a sporophyte. All structures are diploid sporophytes except for some reproductive structures and seed parts.

Question 6

Where are the female reproductive structures located?

Answer 6

The female reproductive structures are in the ovule (part haploid, part diploid). Ovules are located at the base of scales on cones or inside the ovary of flowers.

Question 7

What are the female reproductive structures?

Answer 7

• Megasporangium (2n sporophyte) makes Megaspores (1n)
• Megaspores develop into megagametophytes (very small, sometimes only a few cells)
• Megagametophyte produces the megagametes (eggs)
• The fertilized egg is the zygote (not male and female). Zygote develops into sporophyte.

Question 8

Where are the male reproductive structures?

Answer 8

There are structures in the pollen sac. Located on the cone or the anther of the flower.

Question 9

What are the male reproductive structures?

Answer 9

• Microsporangium (2n) makes microspores (1n)
• Microspores develop into microgametophyte (pollen)
• Microgametophyte produces the microgametes (sperm)

Question 10

Where is the sperm?

Answer 10

Sperm are in the pollen. Pollen is dispersed by wind, insects, or birds.

Question 11

What is pollination?

Answer 11

Pollination is the transfer of pollen to the female plant parts. Some seed plants need water for sperm to swim to eggs after pollination. Other plants produce pollen tubes for the sperm to travel to the egg.

Question 12

What are gymnosperms?

Answer 12

Gymnosperms are plants with ‘naked seeds’. The seeds are exposed/ not inside the fruit.

Question 13

What are examples of the phylum Coniferophyta?

Answer 13

Pines, spruces, cedars, firs

Question 14

What are some features of pines?

Answer 14

• Pines have tough needlelike leaves in clusters.
• Thick cuticle.
• Recessed stomata to reduce water loss.

Question 15

What does “monoecious” mean?

Answer 15

Male and female in the same individual/plant.

Question 16

What develops on each scale in the female cone?

Answer 16

Two ovules, each containing a megasporangium.

Question 17

How many sperm in a mature male gametophyte?

Answer 17

Mature male gametophyte has 2 sperm.

Question 18

Describe the maturation process of the female cone.

Answer 18

• Female cones usually take 2 or more seasons to mature.
• During the first spring, pollen grains drift down between open scales.
• Scales close.
• A year later, female gametophyte matures.

Question 19

Outline pine reproduction.

Answer 19

• Ovules develop in the female cone.
• Mature male gametophyte has 2 sperm.
• Female cone goes through maturation.
• Pollen tube transports sperm to the egg to form a zygote while the other sperm degenerates.
• Seed develops inside the female cone. Seeds contain the embryo, food for the embryo, and the seed coat.