Chapter 2: Cells, Viruses and Reproduction of Living Things

Question 1

2.5 Sexual reproduction in plants

What are the 2 life cycle phases of plant gametogenesis?

Answer 1

1. sporophyte generation
2. gametophyte generation

Question 2

2.5 Sexual reproduction in plants

What occurs in sporophyte generation?

Answer 2

Diploid spores are formed via meiosis.
The zygote undergoes mitosis becoming a sporphyte and then via meiosis becoming diploid spores.

Question 3

2.5 Sexual reproduction in plants

What occurs in gametophyte generation?

Answer 3

Haploid gametes are formed via mitosis.
The diploid spores become gametophytes via mitosis and then the gametes become a zygote by 2 fusing together.

Question 4

2.5 Sexual reproduction in plants

The phases of gametogenesis are combined in…

Answer 4

flowering plants

Question 5

2.5 Sexual reproduction in plants

In terms of the products of gametogenesis:
The main plant boyd is ….(1)
Parts of the anther and ovary are…(2)

Answer 5

1. Diploid sporophytes
2. Haploid gametophytes

Question 6

2.5 Sexual reproduction in plants

Draw the process of alternation of generation

Answer 6

Question 7

2.5 Sexual reproduction in plants

Draw a labelled diagram of a plant

Answer 7

Question 8

2.5 Sexual reproduction in plants

What makes up the stamen?

Answer 8

Anther and filament

Question 9

2.5 Sexual reproduction in plants

What makes up the carpel?

Answer 9

stigma, style and ovary

Question 10

2.5 Sexual reproduction in plants

How is pollen formed?

Answer 10

Meiosis occurs at the anther creating many pollen grain which contain male gametes

Question 11

2.5 Sexual reproduction in plants

How many pollen sacs does each anther contain?

Answer 11

4-Each have many microspore mother cells (diploid)

Question 12

2.5 Sexual reproduction in plants

Diploid microspores (mother cells) divide by…

Answer 12

meiosis creative haploid microspores, which are the gametophyte generation. The gametes themselves are formed from the gametophyte generation.

Question 13

2.5 Sexual reproduction in plants

Gametes are formed from microspores via…

Answer 13

mitosis.

Question 14

2.5 Sexual reproduction in plants

What does each microspore contain?

Answer 14

Two nuclei. One is the generative nuclei which fuses with the ovule nuclei. The other is the tube nuclei which produces the pollen tube.

Question 15

2.5 Sexual reproduction in plants

What produces ovules in an ovary?

Answer 15

Meosis produces ovules in ovaries

Question 16

2.5 Sexual reproduction in plants

How is an ovule attached to the ovary?

Answer 16

Via placenta which is then covered in a nucellus in a centre of this emryo sac where the gametophyte generation forms.

Question 17

2.5 Sexual reproduction in plants

How does the diploid megaspore form?

Answer 17

It divides to form 4 haploid megaspores. Three of these are degenerate and form the antipodal cells, while one undergoes 3 mitotic divisions leaving an embryo sac containing an egg cell, two polar nuclei, 3 antipodal cells and 2 synergids

Question 18

2.5 Sexual reproduction in plants

What is a synergid?

Answer 18

direct pollen tube growth downwards (toward female gametophyte) and facilitate entrance of tube to embryo sac.

Question 19

2.5 Sexual reproduction in plants

What is an antipodal cell?

Answer 19

provide nutrients to support developing embryo

Question 20

2.5 Sexual reproduction in plants

What is pollination?

Answer 20

• Pollination is the process of transferring pollen from the anthers of one plant to the stigma of another (of the same species).
• After this, a pollen tube grows down the stigma carrying the male gamete to the ovary where it fuses with an ova (fertilisation).
• This will then develop into a fruit.

Question 21

2.5 Sexual reproduction in plants

Draw a diagram describing the formation of an egg cell in plants

Answer 21

Question 22

2.5 Sexual reproduction in plants

What is a pollinator?

Answer 22

Pollinators can be insects (particularly bees), or other animals that can move pollen around (or have the pollen stick to them as they move around).

Question 23

2.5 Sexual reproduction in plants

What is external fertilisation?

Answer 23

• Takes place outside the plant
• Relies on chance
• Male and femail gametes fuse in the environment (usually aquatic)

Question 24

2.5 Sexual reproduction in plants

What is the process of plant fertilisation until germination?

Answer 24

1. Male gamete is contained in pollen grain, while the female gamete is deep in the ovarian tissue.
2. Pollen lands on the surgace of the stigma of the flower during pollination
3. Molecules on the surface of stigma and pollen grain interact.
4. If same species, grain grows (germinates)

Question 25

2.5 Sexual reproduction in plants

What is internal fertilisation?

Answer 25

• Higher chance of fertilisation than external
• Involves males releasing sperm into the females body, in some instances males can deposit a package of sperm for the females to pick up
• More common in land animals

Question 26

2.5 Sexual reproduction in plants

What is the process of plant fertilisation after germination?

Answer 26

1. Pollen tube grows out of tube cell through the stigma and style
2. Tip produces hydrolytic enzymes digesting the style tissue so pollen tube makes it way down the cell
3. Digested tissue acts as a nutrient source for the tube as it grows
4. Generative nucleus travels down pollen tube in the generative cell
5. Nucleus divides to form 2 male nuclei
6. Eventually tip of pollen tube passes through micropule of ovule
7. 2 male nuclei pass through micropyle
8. Double fertilisation occurs
9. One male nuclei fuses with two polar nuclei to form endosperm
10. Endosperm is involved in supplying the embryo plant food
11. Other male nucleus fuses with egg cell to form zygote
12. Seed and embryo development begins

Question 27

2.5 Sexual reproduction in plants

Draw the process of fertilisation as a labelled diagram

Answer 27