Unit 16 - Reproduction in Plants

Question 1

What is asexual reproduction?

Answer 1

The production of genetically identical offspring from one parent

Question 2

Give advantages and disadvantages of asexual reproduction

Answer 2

Advantages:

• Only one parent is required - this is helpful for organisms which live in desolate environments where finding a mate is difficult
• Can reproduce quickly - large quantities of offspring can be produced quickly to rapidly populate an area. This helps to dominate a habitat and prevent competition from other species.
• It takes less energy to reproduce

Disadvantages:

• Lack of diversity - all offspring are genetically identical
• Cannot adapt - organisms are adapted to one environment and cannot adapt to changes. If the environment changes e.g. the temperature rises, they are likely to be killed
• Prone to Extinction - as each organism produced is genetically identical, a disease which harms one will be dangerous to all of them, thus it is easy for the whole population to be destroyed by one pathogen

Question 3

What is sexual reproduction?

Answer 3

Sexual reproduction is a process involving the fusion of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other

Question 4

Define fertilisation

Answer 4

The fusion of the nuclei from two gametes (sex cells)

Question 5

State the difference in the number of chromosomes in a gamete nucleus compared with a zygote nucleus

Answer 5

Gametes have haploid nuclei (23 chromosomes) whereas zygotes have diploid nuclei (23 pairs of chromosomes)

Question 6

Give one advantage and one disadvantage of sexual reproduction

Answer 6

• Advantage - It introduces variation
• Disadvantage - It is slower and produces a limited amount of offspring

Question 7

Label the insect pollinated flower below

Answer 7

Question 8

What is the function of the sepals in an insect pollinated plant?

Answer 8

The sepal is a hard coating that protects the developing flower in a bud

Question 9

What is the function of the petals in an insect pollinated plant?

Answer 9

The petals attract the insects so that they can pollinate the plant

Question 10

What is the function of the anthers in an insect pollinated plant?

Answer 10

The anthers contain the pollen sacs which contain the male sex cells of the plant

Question 11

What is the function of the stigma in an insect pollinated plant?

Answer 11

These are the sticky parts of the plant designed to capture the pollen grains

Question 12

What is the function of the ovaries in an insect pollinated plant?

Answer 12

They contain ovules which will grow into seeds when they are fertilised by pollen

Question 13

Label the diagram of a wind pollinated plant below

Answer 13

A - Stigma

B - Anthers

Question 14

What type of pollen grain is this and why?

Answer 14

Pollen from an insect pollinated plant as it has spikes on it to make it stick to insects so they can carry the pollen to another plant

Question 15

What type of pollen grain is this and why?

Answer 15

Pollen from a wind pollinated as it is smooth so that it can be carried by the wind easily

Question 16

What is pollination?

Answer 16

Where pollen grains are transferred from the anthers to the stigma

Question 17

What is self-pollination?

Answer 17

Where pollen grains are transferred from the anthers to the stigma of the same plant

Question 18

What is cross-pollination?

Answer 18

Where pollen grains are transferred from the anthers of one plant to the stigma of another plant of the same species

Question 19

Give one advantage of self-pollination

Answer 19

There is a greater chance of fertilisation as it does not rely on pollinators

Question 20

Give one disadvantage of self-pollination

Answer 20

Genetic variation decreases and the plant is less able to adapt to the environment

Question 21

Give one advantage of cross-pollination

Answer 21

There is increased genetic variation so the plants are more able to adapt to environmental change

Question 22

Give one disadvantage of cross-pollination

Answer 22

The plants are reliant on insect populations for fertilisation

Question 23

Describe what happens when a pollen grain lands on the stigma of a plant

Answer 23

• A pollen tube grows through the style to reach the ovule in the ovary
• The nucleus from the pollen grain then travels down the pollen tube to reach the ovule and fertilise it

Question 24

When does fertilisation in a plant occur

Answer 24

When the nucleus of a pollen grain fuses with the nucleus of an ovule

Question 25

State 3 environmental conditions that affect seed germination

Answer 25

• Oxygen availability
• Water availability
• temperature

Question 26

What is the function of the petal in an insect pollinated plant?

Answer 26

It is colourful to attract the insects

Question 27

What is the function of the style?

Answer 27

The style allows the passage of the pollen tube to the ovary

Question 28

What is function of the nectary?

Answer 28

It gives out sugary liquid to attract insects

Question 29

What is the function of the filament?

Answer 29

The function of the filament is to simply hold up the anther, extending it up to an accesible part of the flower for pollinators to reach or in a wind pollinated plant for the wind to disperse the pollen

Question 30

What are the features of Wind Pollinated Plants?

Answer 30

• Anthers are exposed to the wind so that pollen can easily be blown away
• Stigma hang outside the flower and are feathery to catch pollen carried on wind
• No scent or nectary as there is no need to attract insects
• Petals are small and green as there is no need to attract insects
• Pollen grains are very small and light so they can be carried easily by the wind

Question 31

What are the features of insect pollinated plants?

Answer 31

• Pollen often has spikes to attach to insects
• Large brightly coloured petals to attract insects
• Nectary releases nectar and a scent to attract insects