Plant reproduction

Question 1

Sexual Reproduction:

Answer 1

The fusion of the nuclei of male and female gametes to form a zygote
INVOLVES GAMETES AND FERTILISATION

Question 2

Asexual Reproduction:

Answer 2

The process resulting in genetically identical offspring being produced from one parent
DOES NOT INVOLVE GAMETES OR FERTILISATION

Question 3

Advantages and Disadvantages of Sexual Reproduction:

Answer 3

Increases genetic variation
Species can adapt to new environments due to variation
Disease less likely to affect population (due to variation)
Takes time and energy to find mates
Difficult for isolated members of the species to reproduce

Question 4

Advantages and Disadvantages of Asexual Reproduction:

Answer 4

Population can be increased rapidly
Can exploit suitable environments quickly
More time and energy efficient
Reproduction completed much faster
Limited genetic variation - Offspring genetically identical to parents
Population vulnerable to changes in conditions
Disease likely to affect whole population (as there is no variation)

Question 5

Differences between Sexual and Asexual

Answer 5

A: 1 Parent S: 2
A: Mitosis S: Meiosis
A: Genetically Identical S: Genetically unique
A: Variation in mutation S: 50% of DNA from both parents, new gametes by meiosis
A: Large number of offspring produced S: Relatively limited numbers
A: Relatively fast S: Relatively slow

Question 6

Fertilisation

Answer 6

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

Question 7

Flowers are:

Answer 7

Reproductive organs of plants

Question 8

Pollination:

Answer 8

Plants produce pollen (containing a nucleus inside which is the male gamete) via the anther
The pollen is transferred to the stigma via insects or wind

Question 9

Sepal:

Answer 9

Protects unopened flower

Question 10

Petals:

Answer 10

Large and brightly coloured in insect-pollinated flowers to attract insects
Small and dull in wind-pollinated flowers

Question 11

Anther:

Answer 11

Produces and releases pollen

Question 12

Stigma:

Answer 12

Top of the female part of the flower which collects pollen grains

Question 13

Ovary:

Answer 13

Produces ovum (the female sex cell)

Question 14

Ovule:

Answer 14

Contains ovum (found inside the ovary)

Question 15

Stamen

Answer 15

Consists of the anther and filament

Question 16

Carpel

Answer 16

Consist of stigma, style and ovary

Question 17

Nectary

Answer 17

Produces sugary nectar to attract insects

Question 18

Differences between insect and wind pollinated plants:

Answer 18

Stamens and Stigma enclosed within flower vs exposed
Sticky Stigma vs Feathery Stigma
Large and colourful petals vs small and dull (usually green)
Nectaries present vs absent
Pollen grains large and sticky, with hooks to stick to insect vs small, smooth and light

Question 19

Process of fertilisation in a plant

Answer 19

Insect carries pollen to the stigma
Pollen grain forms pollen tube, grows down style
Pollen reaches the micropyle
Pollen grain nucleus moves down tube to ovary and fuses with ovum
Ovum fertilised, zygote formed and divides, becomes embryonic plant
The ovule containing the embryonic plant becomes the seed
Ovule wall becomes seed coat
Ovary develops into the fruit

Question 20

Conditions for seed germination practical

Answer 20

Set up 4 test tubes each containing 10 seeds on cotton wool, labeling them A, B, C and D
Test tube A: Leave cotton wool dry and at room temp (no water)
Test tube B: Leave cotton wool moist and at room temp (control tube)
Test tube C: Add enough water to cover the cotton wool and seeds, then add a layer of oil and at room temp (no oxygen)
Test tube D: Leave cotton wool moist and in a fridge (no warmth)
Leave all tubes for a set period of time
Compare results: Germination in B
Repeat investigation

Question 21

Germination of seed:

Answer 21

Cotyledons surround the embryo and contain food reserves, suppling the seedling with food (and energy)
The cotyledons fulfill this role until the plant grows its own leaves and can make its own food via photosynthesis
After taking in water, the testa (seed coat) splits
This leads to production of the plumule (shoot) and radicle (root)

Question 22

Natural asexual reproduction in plants:

Answer 22

Runners:
Some plants grow side branches(runners), that have small plantlets at their ends
Once they touch the soil, these plantlets will grow roots and the new plantlets will grow and become independent from the parent plant.

Question 23

Artificial asexual reproduction in plants:

Answer 23

Cuttings:
Gardeners take cuttings from parent plants
A section of the parent plant with a new bud is cut off
This cutting can be place into water until new roots grow or can sometimes be placed into soil
These cuttings are then planted and eventually grow into adult plants that are genetically identical to the original plant - This can be produced cheaply and quickly.