4.6.1.3 Advantages and Disadvantages of Sexual and Asexual Reproduction (biology only) Flashcards
1
Q
Advantages of sexual reproduction:
A
- meiosis produces variation in the offspring
- fusion of gametes gives random combination of genes so there is genetic variation in the offspring
- as genetical material comes from both parents
- so better adapted to survive
- as if the environment changes it is likely that an organism in the species will have a characteristic allows them to survive so variation gives a survival advantage by natural selection
- although some individuals may die, variation decreases the chance of the whole species becoming extinct
- natural selection can be speeded up by humans in selective breeding to increase food production
- this type of reproduction mixes the genetic information of 2 organisms
- organisms with different desirable characteristics can be bred to produce offspring with even more desirable characteristics - speeds up natural selection
- e.g. can increase food production by breeding 2 animals with lots of meats
- can colonise new areas by seed dispersal so can escape any adverse events in original area (for plants)
- many offspring so higher probability some will survive
2
Q
Disadvantages of sexual reproduction:
A
- 2 parents needed - so not possible for isolated individual to sexually reproduce
- requires more time and energy as need to find a mate (for sexual reproduction)
- sexual reproduction is much slower than asexual reproduction
- identical offspring (that are identical to parents) cannot be produced when conditions are favourable
3
Q
Advantages of asexual reproduction:
A
- only one parent is needed so asexual reproduction is more time and energy efficient as do not need to find a mate
- takes less time - faster than sexual reproduction
- many genetically identical offspring can be produced when conditions are favourable so successful trait passed on
- colonisation of local areas
- not wasteful of flowers/pollen/seeds (for plants)
4
Q
Disadvantages of asexual reproduction:
A
- variation cannot be produced in offspring so if the environment changes no individuals will have a survival advantage due to there being no variation - increases the chance of the whole species becoming extinct
- natural selection for that specific species cannot be sped up by humans through selective breeding - so things like food production cannot be increased
5
Q
Selective breeding:
A
the process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with desirable phenotypes
6
Q
Cuttings:
A
- the simplest method of cloning plants
- a branch is cut from a parent plant and is replanted in compost after removing the lower leaves
7
Q
Malarial parasites:
A
- cause malaria
- spread by mosquitoes and are transferred to humans through a mosquito bite
8
Q
How do malarial parasites reproduce sexually and asexually?
A
- malarial parasites reproduce sexually in the mosquito
- they then reproduce asexually in the human host (in the liver and blood cells)
9
Q
Process of reproduction for malarial parasites:
A
- sexual forms of the malarial parasite (Plasmodium) are transferred to a mosquito in a blood meal
- sexual reproduction of the Plasmodium takes place in the mosquito
- the mosquito feeds on another human
- Plasmodium is transferred to the human by the saliva of the mosquito
- Plasmodium feeds, grows and asexually reproduces in the liver
- cells of the parasites invade red blood cells
- Plasmodium asexually reproduces in red blood cells
- sexual forms of the malarial parasite are produced
10
Q
How do fungi reproduce sexually and asexually?
A
- fungi reproduce asexually by producing spores (genetically identical) which land and become new fungi
- when the conditions change in order to increase variation and avoid extinction spores are produced sexually
11
Q
Process of reproduction for fungi:
A
- if the environment changes and the mycelium meets a different strain of fungi sexual reproduction can occur
- 2 haploid cells fuse (fertilisation) to produce a diploid zygote
- meiosis will occur again to produce haploid spores
- sexual reproduction increases genetic variation for the fungi so increases chance of survival - survival advantage, decreases chances of extinction
- in favourable conditions fungi reproduce very quickly via asexual reproduction
- spores are released from mature fungi - they colonise an area and then develop into mature fungi - cycle then continues
12
Q
How do plants reproduce sexually?
A
- many plants reproduce sexually by using pollen (from anthers) which must reach the egg cells in the female reproductive organs (ovaries) of another plant - pollination
- producing seeds (sexually)
13
Q
How do plants reproduce asexually?
A
- strawberry plants reproduce asexually as they produce runners - new identical plants grow off the runner
- daffodils reproduce asexually
- they grow from bulbs
- new bulbs grow from the main one producing a new identical plant
14
Q
Advantage of asexual reproduction in plants:
A
- runners on strawberry plants - allows plant to quickly colonise other areas and spread the plants out
- plants can reproduce even if the flowers have been destroyed by frost or other animals
15
Q
Process of transmission of malarial parasite by mosquitos to humans:
A
- Mosquito takes a blood meal and ingests gametocytes
- Gametocytes develop into sporozoites in the mosquito’s salivary glands
- Sporozoites are passed to humans when the mosquito bites again
- Sporozoites enter the liver where they divide into many merozoites
- Merozoites are released from the liver and enter red blood cells
- Some of these turn into schizonts which bursts the red blood cells releasing more merozoites - coincides with fever attacks
- Some merozoites become gametocytes
