Reproduction in Plants Flashcards
How does asexual reproduction work?
- Does not involve sex cells or fertilisation
- Only one parent is required
Define asexual reproduction
A process resulting in genetically identical offsprings from one parent
What happens as a result to offsprings in asexual reproduction?
Genetically identical to the parent and one another
Give an example of asexual reproduction
Binary fission of bacteria
What are the advantages of asexual reproduction?
- Population can be increased rapidly when conditions are right.
- can exploit suitable environments quickly
- more time and energy efficient
- completed much faster than sexual reproduction
What are the disadvantages of asexual repeoduction?
- limited genetic variation in population
- population is vulnerable to changes in condition and may only be suited for one habitat
- disease is likely to affect whole population as there is no genetic variation.
Why is asexual reproduction in crop plants adavatagous?
A plant has good characteristics (High yield, disease resistant) can be made to reproduce asexually and the entire crop will show the same characteristics.
Define sexual reproduction.
A process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote (fertilised egg cell) and the production of offspring that are genetically different from each other.
Define fertilisation.
Fusion of gamete nuclei
Define gamete
A sex cell
How do gametes differ from normal cells?
Half the no. of chromosomes
How many chromosomes are contained in a zygote?
46
How many chromosomes does the nuclei of gamete consist?
23 (Haploid)
How many chromosomes does the zygote consist of ?
23 pairs (Diploid)
What are the adavantages of sexual reproduction?
- increases genetic variation
- the species adapt to new environments due to variation
- disease is less likely to affect population (due to variation).
What’s are the disadvantages of sexual reproduction?
- takes time and energy to find mates
- difficult for isolated members of the species to reproduce.
What is the advantage for crops that usually reproduce sexually?
Variation increases
Able to survive weather conditions
What is the diadvantage for crops that usually reproduce sexually?
May lead to offsprings that are less successful than parent growing.
What is the male gamete in a plant?
pollen
What is the difference in male gamete from a human and a plant?
The plant one is not capable of locomotion
What is the female gamete in a plant?
Stigma
What are the 2 ways pollination takes place?
Insect pollinated
Wind pollinated
What are the two types of wind pollination?
- Self pollination
- Cross pollination
What is the difference in pollen grains repeoduced in insect pollination and wind pollination?
Insects:
- Small amounts
- large
- heavy
- spiky or hv hooks
Wind:
- large amounts
- small
- lightweight
- smooth
Define fertilisation in terms of pollination.
Pollen nucleus fuses with an ovum nucleus
Briefly name the steps it has to go through to fertilise in a flower.
- Stigma
- Style/pollen tube
- Ovary
- Ovules
What are the factors that affect the germination of seeds?
- Water
- Oxygen
- Warmth
How does water affect the germination of seeds?
Allows seed to swell up and the enzymes embryo to start working so that growth can occur
How does the oxygen affect the germination of seeds?
so that energy can be released for germination.
How does warmth affect the germination of seeds?
Germination improves as temp rises (up to max) as the reactions which take place are controlled by enzyme reactions.
Define cross - pollination.
Pollen from one plant is transferred to the stigma of another plant of the same species.
Define self pollination.
Pollen from flower lands on it’s own stigma or the stigma of another flower on the same plant.
How is lack of variation a disadvantage?
Less likely organisms will adapt to suit new conditions.
Define germination
It is the start of growth in the seed.
Define pollination.
Transfer of the pollen grain to the stigma.
