39 & 40 - Plant Reproduction & Vegetative propagation

DIAGRAMS

Give a brief biological explanation for fruit formation by plants

To aid seed dispersal

What is meant by the term vegetative propagation?

Asexual reproduction in plants

Give two methods of vegetative propagation and an example of each

Stem: strawberry (runners)

Root: dahlia

Give three methods horticulturists use to artificially propagate plants

Cutting (e.g. Busy Lizzy)

Grafting (e.g. rosebush)

Micropropagation (e.g. orchids)

Layering (e.g. blackberries)

Which part of the embryo in the seed gives rise to

1. the root

2. the shoot

1. Radicle

2. Plumule

What is meant by seed dispersal?

The scattering or spreading of seeds away from the parent plant

Give two methods of seed dispersal

Wind

Water

Animal

Self

Give one advantage of seed dispersal

To minimise competition for the parent plant /

To colonise new habitats

Name X, Y and Z

X: style

Y: Ovary

Z: Ovule

Give one way other than animals that the pollen grain can be carried to the stigma

Wind

Draw in a pollen tube to show the path taken by the male gametes

Describe how the generative nucleus becomes the male gametes

Generative nucleus divides by mitosis to produce two sperm nuclei

Give an account of the development of the egg cell

Diploid / megaspore mother cell / divides by meiosis / produces four haploid cells / three degenerate / divides by mitosis three times / embryo sack has eight nuclei / one becomes egg cell / two polar nuclei

Describe what happens in double fertilisation

Egg cell fuses with one sperm nucleus to form a diploid zygote

Two polar nuclei fuse with one sperm nucleus to form triploid endosperm

State the collective term used to describe the anther and the filament of the flower

Stamen

Outline the development of the pollen grains in the anther

Diploid / mother cell / divides by meiosis / to produce four haploid cells / divides by mitosis / pollen grain with two nuclei / generative nucleus / tube nucleus

What is pollination?

The transfer of pollen from the anther to the stigma

Give two methods of pollination

Animal

Wind

State the location where food is normally stored in a:

1. monocotyledonous seed

2. dicotyledonous seed

1. Endosperm

2. Cotyledon

Describe how seeds contribute to the formation of fruit

The seed produces growth regulator

Name the part of the flower that becomes the fruit

Ovary

Outline one role of genetics in fruit production

Seedless fruit or more advantageous traits

Describe the role of each of the following in germination:

1. Digestion

2. Respiration

1. Makes nutrients available

2. Release of energy from food in the form of ATP

State the function of the nucleus X

Forms the pollen tube

Describe what happens to the generative nucleus following pollination

Divides by mitosis

Label the structures A, B, C and D

A: Anther

B: filament

C: Ovary

D: Stigma

Is this plant insect or wind pollinated?

Give two reasons for your answer

Wind

Large stigma (or anther)/ feathery stigma / stigma (or anther) outside the flower / long style (filament)

What is the role of parts A and D?

A: produce pollen

D: trap pollen

Give one disadvantage of self pollination

Less variation or offspring more susceptible to disease

Which labelled part develops into the fruit?

C - ovary

How are seedless fruits developed?

Sprayed with growth regulators or auxins

State two advantages of sexual reproduction versus asexual reproduction in plants

Variation / seed dispersal / less competition / less disease

Describe in detail the development of the embryo sac from a megaspore mother-cell

• Embryo sac mother-cell (diploid) divides by meiosis

• Four haploid cells produced

• Three degenerate, haploid embryo sac remaining

• Undergoes mitosis x3 giving eight nuclei

• Embryo sac swells with food from nucellus

• Five nuclei degenerate

• Two polar nuclei and one egg cell remain. These are the female gametes

Give two features of vegetative propagation

One parent / no gametes (or no seeds) / no variation

Give one example of natural vegetative propagation from and leaf and one example from a bud

Leaf: plantlets (cactus)

Bud: Bulb (Daffodil / onion)

Suggest a benefit of artificial vegetative propagation

Rapid / desirable characteristics maintained

What structure leads to the formation of the seed’s testa?

Integumens

Name two biomolecules stored in endosperm or cotyledon tissue

Lipids / carbohydrates / protein / vitamins

Give one way knowledge of seed dormancy has been useful to humans

How to store seeds or maximise the growing season

Suggest why the measurement of dry mass is preferred in investigations

Water content can vary between seeds

Explain why the dry mass of the endosperm tissue decreases over the three weeks

Food is transferred to the embryo or respiration is occurring for energy or loss of CO₂

What process begins at A?

Photosynthesis

Would you expect the total dry mass of the seed (embryo + endosperm) to have remained the same up to A

No

it will lose mass due to respiration / loss of CO₂