Sexual Reproduction in Flowering Plants: Biology questions

Section A: objective questions

12 marks

Choose the best answer for each question.

Which two parts make up the stamen of a flower?

Filament and anther
Stigma and style
Ovary and ovule
Petal and sepal

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The stamen, the male organ, consists of the filament and the anther.

For the teacher: Remembering, low difficulty, standard 6.1

Textbook p. 114

Which part of the flower receives the pollen grains?

Anther
Filament
Stigma
Ovule

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The stigma is the top of the carpel and receives pollen.

For the teacher: Remembering, low difficulty, standard 6.1

Textbook p. 115

Which statement is true of a bisexual flower such as a lily?

It has only stamens
It has both stamens and a carpel in the same flower
It has only a carpel
It has no petals

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A bisexual flower (hermaphrodite) has male and female organs in the same flower.

For the teacher: Understanding, low difficulty, standard 6.1

Textbook p. 114

Pollen grains develop from diploid cells in the pollen sacs. What are these cells called?

Megaspore mother cells
Generative cells
Polar cells
Microspore mother cells

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Pollen grains form from microspore mother cells (2n).

For the teacher: Remembering, low difficulty, standard 6.2

Textbook p. 116

A microspore mother cell divides by meiosis. What is produced?

Two diploid cells
Two haploid cells
Four haploid cells forming a tetrad
Four diploid cells

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Meiosis gives four haploid microspores (a tetrad), which develop into pollen grains.

For the teacher: Understanding, low difficulty, standard 6.2

Textbook p. 117

One megaspore cell divides by mitosis three times. How many nuclei does the embryo sac contain?

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1 to 2 to 4 to 8 nuclei: three mitotic divisions give eight.

For the teacher: Applying, medium difficulty, standard 6.2

Textbook p. 119

What is pollination?

The fusion of a male gamete and an egg cell
The growth of the pollen tube
The formation of the seed
The transfer of pollen grains from the anther to the stigma

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Pollination is the transfer of pollen grains from the anther to the stigma.

For the teacher: Remembering, low difficulty, standard 6.3

Textbook p. 120

What happens to the tube nucleus when the pollen tube reaches the embryo sac?

It fuses with the egg cell
It degenerates
It divides to form two male gametes
It becomes the endosperm

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The generative nucleus gives two male gametes. The tube nucleus degenerates.

For the teacher: Understanding, low difficulty, standard 6.3

Textbook p. 121

A male gamete fuses with the two polar nuclei. What is formed?

Triploid endosperm nucleus
Diploid zygote
Haploid egg cell
Tetrad

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Male gamete (n) + two polar nuclei gives a triploid (3n) endosperm nucleus.

For the teacher: Understanding, low difficulty, standard 6.3

Textbook p. 123

After fertilisation, which part of the flower develops into the seed?

Ovary
Ovary wall
Stigma
Ovule

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The ovule becomes the seed; the ovary becomes the fruit.

For the teacher: Remembering, low difficulty, standard 6.4

Textbook p. 125

The pericarp of a fruit develops from which structure?

Integument
Ovary wall
Endosperm
Zygote

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The ovary wall becomes the pericarp (exocarp, mesocarp and endocarp).

For the teacher: Understanding, low difficulty, standard 6.4

Textbook p. 125

Which feature of a seed allows it to be stored for a long time before germinating?

It is produced in large numbers
It is light and spongy
It is dormant
It has a suspensor

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Seeds can become dormant structures, so they survive storage until conditions suit germination.

For the teacher: Understanding, low difficulty, standard 6.5

Textbook p. 128

Section B: structured questions

33 marks

Answer all questions. Write your answers in the spaces provided.

Diagram 1 shows a longitudinal section of a flower.

Longitudinal section of a flower with the labels visible — Diagram 1

[2 marks] (a)State the name of the male reproductive organ and the female reproductive organ of the flower.

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Male: stamen [1]1
Female: carpel [1]1

Tick each point you got.

[2 marks] (b)Name the part of the carpel that becomes the fruit, and the part that receives pollen.

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Ovary [1]1
Stigma [1]1

Tick each point you got.

For the teacher: Remembering, low difficulty, standard 6.1

Textbook p. 114

A microspore mother cell in an anther produces pollen grains.

[1 mark] (a)Name the type of cell division that forms the tetrad.

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Meiosis [1]1

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[3 marks] (b)The nucleus of a pollen grain divides by mitosis. Name the two nuclei formed and state what happens to each when the pollen tube reaches the embryo sac.

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Generative nucleus and tube nucleus [1]1
The generative nucleus divides to form two male gametes [1]1
The tube nucleus degenerates [1]1

Tick each point you got.

For the teacher: Understanding, low difficulty, standard 6.2

Textbook p. 117

The embryo sac forms from a megaspore mother cell in the ovule.

[2 marks] (a)How many megaspore cells are formed by meiosis, and how many develop further?

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Four [1]1
One (three degenerate) [1]1

Tick each point you got.

[2 marks] (b)The surviving cell divides by mitosis three times. Calculate the number of nuclei formed.

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2 × 2 × 2 [1]1
8 nuclei [1]1

Tick each point you got.

For the teacher: Applying, medium difficulty, standard 6.2

Textbook p. 119

Diagram 2 shows a pollen tube reaching an embryo sac.

Pollen tube in the style reaching the embryo sac with labelled cells — Diagram 2

[1 mark] (a)Through which opening does the pollen tube enter the ovule?

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Micropyle [1]1

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[4 marks] (b)Describe the two fusions of double fertilisation and name the product of each.

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Male gamete fuses with egg cell [1]1
Gives diploid zygote [1]1
Second male gamete fuses with two polar nuclei [1]1
Gives triploid endosperm nucleus [1]1

Tick each point you got.

For the teacher: Analysing, medium difficulty, standard 6.3

Textbook p. 123

A fungus damages the stigma of a flower so that pollen grains cannot germinate on it.

[2 marks] (a)Predict whether the flower can form a seed. Give a reason.

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No [1]1
The pollen tube cannot form and carry the male gametes to the embryo sac, so fertilisation does not occur [1]1

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[3 marks] (b)Explain why double fertilisation is important for the survival of the plant species.

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Zygote passes genetic information to the next generation [1]1
The zygote restores the diploid number [1]1
The endosperm supplies food for the embryo, so it can stay alive in the seed until germination [1]1

Tick each point you got.

For the teacher: Evaluating, high difficulty, standard 6.3

Textbook p. 124

After fertilisation, the flower changes into a fruit containing seeds.

[2 marks] (a)State what each of these becomes: (i) ovule (ii) ovary wall.

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Ovule: seed [1]1
Ovary wall: pericarp of the fruit [1]1

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[3 marks] (b)Name the three layers of the pericarp.

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Exocarp [1]1
Mesocarp [1]1
Endocarp [1]1

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[1 mark] (c)State the function of the suspensor.

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Anchors the embryo to the wall of the embryo sac [1]1

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For the teacher: Understanding, low difficulty, standard 6.4

Textbook p. 125

A farmer stores dried long bean seeds for the next planting season.

[3 marks] (a)Explain how a seed is able to survive storage.

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The seed is dormant [1]1
Metabolism is very slow so it uses little food [1]1
The strong testa is waterproof and protects the embryo from spoiling [1]1

Tick each point you got.

[2 marks] (b)Suggest why a plant that produces many seeds has a better chance of survival.

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More seeds mean more chances that some germinate and grow [1]1
Even if many are eaten or land in unsuitable places [1]1

Tick each point you got.

For the teacher: Evaluating, medium difficulty, standard 6.5

Textbook p. 128

Section A: objective questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Section B: structured questions

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19