Reproduction in Plants

Question 1

What is sexual reproduction?

Answer 1

Is when there are two parents and there are two gametes which fuse in fertilisation and the offspring shares the genes of both parents.

Question 2

What is asexual reproduction?

Answer 2

Is when there is only one parent, no gametes and no fertilisation occurs. The offspring is genetically identical to the parent.

Question 3

What are the advantages of sexual reproduction?

Answer 3

-Variation
-Adapt and evolve quicker
DIS: slower, longer to grow family, don’t pass on many of your genes

Question 4

What are some aspects of sexual reproduction in plants

Answer 4

1. Sex cells are formed by meiosis
2. Pollen grains are produced in the anther of the stamen
3. Pollen contains the plant’s male gametes called sperm
4. Ova are produced in the ovules and are the female gamete

Question 5

What are the different ways pollination can occur?

Answer 5

Wind, Insect

Question 6

How is the position of the stamen different for wind pollinated and insect pollinated flowers?

Answer 6

• Wind: Exposed so that wind can easily blow pollen away

- Insect: Enclosed within flower so that insect must make contact

Question 7

How is the position of the stigma different for wind pollinated and insect pollinated flowers?

Answer 7

• Wind: Exposed to catch pollen blowing in the wind (hanging outside flower)
• Insect: Enclosed within flower so that insect must make contact

Question 8

How is the type of stigma different for wind pollinated and insect pollinated flowers?

Answer 8

• Wind: Feathery to catch pollen blowing in the wind

- Insect: Sticky so pollen grains attach from insects

Question 9

How is the size of petals different for wind pollinated and insect pollinated flowers?

Answer 9

• Wind: Small

- Insect: Large to attract insects

Question 10

How is the colour of petals different for wind pollinated and insect pollinated flowers?

Answer 10

• Wind: Not brightly coloured, usually green (not waste energy to make this as not needed?)
• Insect: Brightly coloured to attract insects

Question 11

How is the nectaries different for wind pollinated and insect pollinated flowers?

Answer 11

• Wind: Absent

- Insect: Present (nectar is a ‘reward’ for insects)

Question 12

How is the pollen grains different for wind pollinated and insect pollinated flowers?

Answer 12

• Wind: Smaller, smooth inflated grains to carry in the wind (large quantity)
• Insect: Larger, sticky grains to stick to insects’ bodies

Question 13

Why do plants generally ensure that they cross pollinate?

Answer 13

Greater chance of genetic variation

Question 14

What is fertilisation?

Answer 14

The fusion of female and male gametes to produce a zygote in sexual reproduction, that undergoes cells division and develops into an embryo

Question 15

Describe plant fertilisation

Answer 15

1. Pollen lands on stigma on carpel
2. Pollen tube grows down the style and enters the ovary and then enters the ovule through the micropyle
3. The pollen then enters the ovum where it is fertilised to become a zygote
4. There are also polar nuclei which are also fertilised to form cotyledons which provide a food source to the zygote

Question 16

What is the female part of the plant called?

Answer 16

The carpel

Question 17

What is the function of the stigma?

Answer 17

The platform on which the pollen lands

Question 18

What is the function of the style?

Answer 18

A stalk which holds and supports the stigma in the best position

Question 19

What is the function of the ovary?

Answer 19

A hollow chamber which contains the female gametes inside ovules. The ovules develop to form the walls of the ovary

Question 20

What is the function of the micropyle?

Answer 20

Entry point for the male nucleus at fertilisation

Question 21

What is the male part of the plant called?

Answer 21

The stamen

Question 22

What is the function of the anther?

Answer 22

Contains four pollen sacs filled with pollen grains. Each pollen grain contains a male gamete.

Question 23

What is the function of the filament?

Answer 23

A long stalk that holds and supports the anther in the best position to release pollen onto a visiting insect.

Question 24

What is cross pollination?

Answer 24

Cross pollination is when pollen from a flower is transferred to the stigma of another flower (Sexual reproduction). They rely on insects or wind to help them pollinate.

Question 25

What is self pollination?

Answer 25

Self pollination occurs when pollen from a flower is transferred to it's own stigma

Question 26

What is pollination?

Answer 26

The transfer of pollen from an anther to a stigma, so that the male gametes can fertilise the female gametes in sexual reproduction

Question 27

Describe seed and fruit formation

Answer 27

1. The zygote, (having been fertilised), develops into an embryonic plant with a small root (radicale) and small shoot (plumule) 2. The other contents of the ovule develop into cotyledons which will be a food store for the young pant when the seed germinates. Some plants have one cotyledon (monocots) and some have two (dicots). 3. The ovule wall hardens and becomes the testa or seed coat 4. The ovary wall swells and becomes the fruit coat, this can take many forms depending on the type of fruit

Question 28

Why do seeds disperse?

Answer 28

Too avoid competition of water, mineral ions and oxygen.

Question 29

What are the different types of seed dispersal?

Answer 29

- Wind - Water - Animal (internal and external) - Ballistic (explosive)

Question 30

Why are seeds able to lie dormant?

Answer 30

- Because they are not using energy to grow when the conditions are not right (slow metabolism, very little respiration (like extreme hibernation)). - When seeds are dispersed from the parent plant they are usually very dry and only contain 10% water. This low water content restricts a seed's metabolism.

Question 31

What happens when a seed germinates?

Answer 31

- Dormancy is broken | - The seed's food store is broken down by enzymes respired aerobically

Question 32

What conditions are needed for germination?

Answer 32

1. Warm temperatures, so that enzymes can act efficiently (suitable temperature as depends on what type of seed it is) 2. Water, to soften the testa and for chemical reactions in the seed to take place in solution 3. Oxygen, for respiration (which provides energy for growth) (4. pH (of soil) )

Question 33

Describe germination

Answer 33

1. The seed takes in water and starts to grow using its store of energy 2. The first root starts to grow down into the soil 3. The shoot grows up 4. Finally extra roots grow and the first green leaves appear.

Question 34

Describe how germinating seeds get energy from food stores

Answer 34

1. A developed seed contains an embryo and a store of food reserves, wrapped in a hard seed coat 2. When a seed starts to germinate, it gets glucose for respiration from its own food store. This gives it the energy it needs to grow. The radicle breaks through the testa and grows downwards into the soil (positive geotropism). The plumule grows upwards towards the light (negative geotropism) 3. Once the plant has grown enough to produce green leaves it can get its own food for energy from photosynthesis.

Question 35

Describe how plants reproduce asexually using natural methods

Answer 35

E.G Strawberry 1. The parent strawberry plant sends out runners, fast-growing stems that grow out sideways just above the ground 2. The runners take root at various points (a short distance away) and new plants start to grow) 3. The new plants are clones of the parent strawberry plant so there is no genetic variation between them

Question 36

Describe how plants reproduce asexually using artificial methods

Answer 36

1. Gardeners can take cuttings from a good parent plant and then plant them to produce genetically identical copies (clones) of the parent plant 2. These plants can be produced quickly and cheaply

Question 37

Suggest a way in which animal and plant asexual reproduction must be different

Answer 37

A zygote is produced without fertilisation

Question 38

What is fertilisation?

Answer 38

Fertilisation involves the fusion of a male and female gamete to produce a zygote that undergoes cell devision and develops into an embryo

Question 39

What is germination?

Answer 39

The process by which the embryo plant in the seed starts to grow to the point where it is photosynthesising independently