16.1 - 16.3 Reproduction in plants

Question 1

asexual reproduction

Answer 1

a process of resulting in the production of genetically identical offspring from one parent

Question 2

binary fission

Answer 2

when bacteria produce exact genetic copies of themselves in a type of asexual reproduction

Question 3

state and explain types of asexual reproduction in plants

Answer 3

1. Bulbs and tubers - these are food storage organs from whcih budding can occur and produce new plants that are genetically identical to parent plant
2. Runners - some plants grow shoots that contain tiny plantelets on them (e.g. strawberries). These will grow roots and develop into seperate plants that are genetically identical to parent plant.

Question 4

Advantages of ASEXUAL reproduction

Answer 4

1. pop can be increased rapidly when conditions are right
2. can exploit suitable environments quickly
3. more time and energy efficient
4. reproduction is completed much faster than sexual

Question 5

Disadvantages of ASEXUAL repoduction

Answer 5

1. Limited genetic variation in pop
2. pop is vulnerable to changes in conditions - only suited for one habitat
3. disease more likely to affect the whole pop bcs no genetic variation

Question 6

Advantages and Disadvantages of ASEXUAL reproduction for CROPS

Answer 6

+) varieties with useful features can be cloned in large numbers

-) all clone plants are susceptible to the same disease

Question 7

Sexual reproduction

Answer 7

a process involving the fusion of the nuclei of two gametes to form a zygote and the production of genetically different offspring

Question 8

fertilisation

Answer 8

fusion of the nuclei of gametes

Question 9

whats special about the nuclei of gametes?

Answer 9

they are haploid nuclei - contains only one set of chromosomes (23, no pairs)

Question 10

Advantages of SEXUAL reproduction

Answer 10

1. Increases genetic variation
2. species can adapt to new environment bcs variation, giving them a survival advantage
3. disease less likely to affect pop (due to variation)

Question 11

Disadvantages of SEXUAL reproduction

Answer 11

1. takes time and energy to find mates
2. difficult for isolated members of the species to reproduce

Question 12

Advantages and disadvantages of SEXUAL reproduction in CROPS

Answer 12

(+) speed up natural selection through selective breeding - increasing yield
(-) takes a long time to grow new crops. Is dependent on sucessful pollination.

Question 13

sepal

Answer 13

protects the unopened flower

Question 14

petal

Answer 14

may be brightly coloured to attract insects

Question 15

anther

Answer 15

produces and releases the male gamete (pollen grain)

Question 16

stigma

Answer 16

top of female part of the flower - collects pollen grains

Question 17

ovary

Answer 17

produces the female gamete (ovum)

Question 18

ovule

Answer 18

contains the female gamete (found inside the ovary)

Question 19

difference between pollen produced by wind and insect pollinated flowers

Answer 19

INSECT: produce smaller amounts of larger, heavier pollen grains that often contains spikes or hooks on outside to stick to insects better
WIND: large amounts of small, lightweight pollen that are usually smooth

Question 20

difference between flowers on wind and insect pollinated flowers

Answer 20

INSECT: large and brightly coloured to attract insects
WIND: small and dull (often green or brown)

Question 21

difference between scent/nectar in wind and insect pollinated flowers

Answer 21

INSECT: present - entices insects to visit the flower and push past stamen to get nectar
WIND: absent - no need to waste energy

Question 22

difference between anthers and stigmas in wind and insect pollinated flowers

Answer 22

INSECT: Anthers are inside the flower, stiff and firmly attached to brush against insects. Stigmas are sticky so pollen grains can stick when insect brushes past.
WIND: Anthers are outside flower, swiming loose on long filaments to release pollen grains easily. Stigmas are outside flower, feathery to catch drifting pollen grains

Question 23

Cross pollination

Answer 23

occurs when the pollen from one plant is transferred to the stigma of another plant of the same species
- improves genetic variation
- relies completely on pollinators, if pollinators gone (reduction in bees) then no pollination.

Question 24

Self pollination

Answer 24

when the pollen from a flower lands on its own stigma or on the stigma of another flower on the same plant
- reduces genetic variation. less likely that any offspring will have adaptations that suit the new conditions well.

Question 25

how does fertilisation occur in flowers. starting from how the pollen gets to the ovum.

Answer 25

1. pollen grain lands on the stigma
2. the pollen grain grows a tubule down the style using digestive enzymes. Acting as a channel to deliver the male gamete to the female gamete in the ovule.
3. fertilisation occurs when the haploid male and female gametes nuclei fuse and form a diploid zygote. Divides to become embryo, which become seed. the fertilised ovary is a fruit.

Question 26

germination

Answer 26

start of growth in the seed

Question 27

factors required for sucessful germination and why

Answer 27

WATER - allows the seed to swell up and the enzymes in the embryo to start working so that growth can occur
OXYGEN - so that energy can be released for germination
WARMTH - germination improves as temp rises as the reactions which take place are controlled by enzymes

Question 28

Experiment to investigate germination

Answer 28

1. Set up 4 boiling tubes each containing 10 cress seeds on cotton wool
2. Set each test tube as shown in diagram below
3. Leave tubes in set environment for a period of time: A, B and C incubated at 20°C; D placed in a fridge at 4°C
4. Compare results and see which tube has the greatest number of germinated seeds