9.4 Plant reproduction

Question 1

Types of plany reproduction

Answer 1

• Vegetative propagation (asexual reproduction from a plant cutting)
• Spore formations (e.g. moulds, ferns)
• Pollen transfer (flowering plants – angiospermophytes)

Question 2

Stages of sexual reproduction in flowering plants

Answer 2

1. Pollination: transfer of pollen grains from anther - stigma; self-pollination or cross-pollination (improves genetic diversity), with pollinators mutualistic relationship

2. Fertilisation: fusion of male gamete nuclei with female gamete nuclei -> zygote; male gamete inpollen grain, female gamete in ovule

3. Seed dispersal: fertilisation - formation of a seed, seed dispersal reduces competition for resources, seed dispersal mechanisms: wind, water, fruits and animals, seed structure varies on the mechanism of dispersal

Question 3

Flower anatomy

Answer 3

Question 4

What influences flowering?

Answer 4

Photoperiodism: light - darkness periods influence phytochromes (leaf pigments) responsible for detecting

Phytochrome in two forms:

• active - Pfr - converted into inactve when absorbs far red light (725nm), will gradually into inactive in darkness
• inactive - Pr - converted into active when absorbs red light (660nm)

Question 5

Types of flowers based on photoperiodism

Answer 5

Two types of flowering plants:

• Short day: gene for flowering expressed if long darkness periods present
• Long day: gene for flowering expressed if short darkness periods present

Light periods van be manipulated - flowering induced

Question 6

Types of seeds and seed anatomy

Answer 6

Types of seeds:

• monocotyledon - corn
• dicotyledon - bean

Structures:

• Testa – outer seed coat - protects the embryonic plant
• Micropyle – small pore in the outer covering - allows for the passage of water
• Cotyledon – contains food stores and forms the embryonic leaves
• Plumule – embryonic shoot (also called the epicotyl)
• Radicle – embryonic root

Question 7

Conditions needed for germination

Answer 7

• Oxygen – aerobic respiration (seed requires large amounts of ATP to develop)
• Water – metabolically activate the seed
• Temperature – seeds require certain temperature to sprout
• pH – suitable soil pH to sprout (optimal for enzymes)

Som require special conditions: fire, freezing, digestion, washing, scarification

Question 8

±±±±±±±±±±±±Explain double fertilization

Answer 8

Only in flowering plants - 2 sperms fertilise both egg cell (haploid) + food store (diploid) => zygote (diploid) + endosperm (food store) (triploid)

Question 9

Monocotyledons vs dicotyledons

Answer 9

Question 10

Describe germination process

Answer 10