14. Reproduction in plants

Question 1

Describe asexual reproduction and sexual reproduction

Answer 1

1. a process resulting in the production of genetically identical offspring from one parent
2. a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other.

Nuclei of gametes are haploid and that the nucleus of a zygote is diploid.
fertilisation as the fusion of the nuclei of
gametes

Question 2

Advantages and disadvantages of asexual reproduction

Answer 2

1. Reproduce on its own- does not need to wait be pollinated, or to find a mate

Rapid - faster than sexual reproduction.

Less energy used - no need to find a mate, less resources

Offsprings of plants are adapted to environment will inherit same genes, equally adapt and grow. Population can increase when conditions are right.

2. No genetic variation- offsprings genetically identical to parent

Run risk of all their plants being vulnerable to attack by a pester disease

Population is vulnerable to changes in conditions & may only be suited to one habitat

Question 3

Advantages and disadvantages of sexual reproduction

Answer 3

1. Genetic variation, species can adapt to new conditions, can colonise new areas, seed disperse which spread far away from parents so less competition with parent plant.

survive through harsh conditions, allows natural selection to occur, genes different from parent plant, allows mutation to be expressed, cross pollination, offsprings resistant to diseases.

2. Takes time and energy to find mates
   Difficult for isolated members of species to reproduce

Question 4

Parts of an insect-pollinated flower

Answer 4

sepals- protect the flower while it is a bud

petals- brightly colored structure that attracts I or B to flower

–stamens- male part of flower

filaments- stalk part of stamen- long connecting anther

anthers- pollen grains are made, contain male gametes

–carpels- female part of flower

style- connects stigma to ovary

stigma- catch/ receive/ collect pollen grains

ovary- holds ovules

ovules- contains female gametes

Question 5

Describe the structural adaptations of insect-pollinated and wind-pollinated flowers

Answer 5

I- large, petals, nectars at base of petal, anthers and sticky stigma inside flower where insects have to brush past them to react nectar, spiky and sticky pollen which sticks to insects, large quantities of larger and heavier pollens made because some will be eaten or delivered to wrong flower

W- small, no petals, no scent or nectar, anthers- catch wind and stigma- large and feathery so pollen may land on it, both dangle outside the flower, smooth light pollen which can be blown in the wind, very large quantities made because most will be blown away and lost.

Question 6

Describe pollination, self-pollination and cross-pollination,

Answer 6

transfer of pollen grains from an anther to a stigma

the transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the
same plant.

the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species

Question 7

Advantages and disadvantages of self-pollination

Answer 7

A- fast,
can colonise new areas quickly- offspring will be well adapted to conditions near parent if environment does not change
no reliance on pollinators
greater chance of pollination
less wastage of pollen

D- little/no variation- genetic diversity,
will not be able to adapt to change in the environment, becoming homozygous
variation is due to mutation,
low chance that mutation will be expressed,
risk of extinction
increase chance of genetic disease
no evolution, may become extinct

Question 8

Advantages and disadvantages cross-pollination

Answer 8

A- allows, variation / genetic diversity ;
plant more likely to survive (named) environmental change ;
resistance to disease ;
(ability to) evolve

D- 1 reliant on (named) pollinators / wind ;
2 wastage of pollen / less chance of pollination ;
3 idea of more energy required ;
4 need to produce, more pollen / flowers / nectar ;
5 needs more than one plant ;
6 risk of less, fertilisation / reproduction ;

Question 9

Fertilisation in plants and condition of seed

Answer 9

If the pollen grain has landed on the right kind of stigma, it begins to grow a tube, down through the style and ovary, towards the ovule. It secretes enzymes to digest a pathway through style.

Inside the ovary, the ovules start to grow. Each ovule now contains a zygote, formed at fertilisation- pollen nucleus (male gamete) fuses with a nucleus in ovule (female gamete ) zygote divides by mitosis to form an embryo plant, ovule is now a seed

Question 10

Conditions that affect germination of seeds and condition of seed after fertilisation

Answer 10

water, oxygen and a suitable temperature

seed is dehydrated. Dormant - inactive, with metabolic reactions taking place slowly or not at a which is good as it can survive harsh conditions (cold or drought, which would kill a growing plant)

Question 11

prevent cross-pollination between genetically modified plants and wild varieties of plants

Answer 11

grow, GM / wild varieties, in glasshouses ;
cover flowers ;
remove stamens ;
plant another species around the crop ;
make a large, gap / wall, around the field ;
use sterile GM plants ;
grow female plants (only)