UNIT 2 Flashcards
Genetic diversity.
Genetic variation between individuals is measured by the population’s gene pool (sum of different genes and alleles).
Why is genetic diversity important?
- Guards against environmental changes, like new diseases or predators.
- The larger the gene pool is the greater the population’s resilience to to environmental changes. This is because a population with a greater number of alleles are more likely to contain alleles that are well-adapted to survive environmental challenges.
Sexual reproduction.
fusion of 2 distinctive haploid gametes to produce a single diploid zygote with 2 sets of chromosomes.
Reproductive strategies.
adaptations to reproduction that improve the success of a species’ survival.
Fertilisation.
the process where 2 gametes fuse to create an egg (zygote).
zygote
diploid cells formed by 2 haploid cells.
Oviparity
eggs released into the external environment.
Viviparity
the embryo develops inside of the mother.
Advantages of sexual reproduction.
- Increases genetic diversity, and allows recombinment of offspring.
- Improves resilience.
- Reduces change of offspring developing a disorder.
Disadvantages of sexual reproduction.
- time and energy it takes to find and attract a mate.
- Risk of transferring diseases associated with intercourse.
Asexual reproduction.
Producing offspring without the fusion of gametes.
Cloning
A genetically identical
organism or section of DNA
Binary Fission
a type of asexual reproduction where one organism divides into two identical organisms
Types of asexual reproduction.
- Budding.
- Fragmentation.
- Vegetive Propagation.
- Sporogensis.
- Parthenogenesis
Budding
Cells form a bud and break away to form a clone.
Fragmentation
Parent breaks into fragments which may develop into clones
Vegetive Propagation
The plant grows from fragments eg. roots or cuttings from parent
Sporogensis.
spores disperse from the organism onto the surroundings
Spore - small haploid units used
as a means of asexual reproduction
in sporogenesis
Parthenogenesis
An embryo can develop from a single
unfertilised gamete
Advantages of Asexual reproduction.
- Grows faster.
- Offspring is an identical clone of parent.
- Does not require a mate to reproduce.
Disadvantages of Asexual reproduction.
- Genetic diversity is low, and asexually reproducing populations may suffer during rapid environmental change.
reproductive cloning technologies - ANIMALS.
artificially induced human interventions to produce genetically identical clones
- somatic cell nuclear transfer
(SCNT)
- Embryo splitting
Somatic cell nuclear transfer
(SCNT)
the transference of a somatic cell nucleus into an enucleated(a cell that has had its nucleus removed or destroyed) egg cell.
In steps:
1. Enucleation – Destruction/removal of the nucleus from the donator egg so it can be enucleated.
2 Extraction – Extract somatic cells nucleus.
3 Insertion – Insert the nucleus into the egg
4 Development – Develop into an embryo and implanted into surrogate mother.
Embryo splitting
the division of an early embryo into several individual embryos
IVF
The fertilisation of an egg outside
of the body
Reproductive cloning technologies in plants.
- Plant tissue culturing
- Plant cuttings