9 reproductive strategies Flashcards
compare the sexual and asexual reproduction in terms of no. parents and genetic makeup of offspring
Number of parents
- sexual reproduction: two parents
- asexual reproduction: one parent
Genetic makeup of offspring
- sexual reproduction: non-identical
- asexual reproduction: identical
describe two methods of asexual reproduction in animals
Binary fission: process of cell multiplication in bacteria and other unicellular organisms in which there is no formation of spindle fibres and no chromosomal condensation
Mitosis: process involved in the production of new cells genetically identical to the original cell; an essential process in asexual reproduction
describe two methods of asexual reproduction in plants
Vegetative propagation: The plant releases runners from the parent plant that establish their own root system to obtain water and nutrients from the soil. The daughter cells are initially smaller than the parent cells.
- e.g. Strawberry plant
Budding: A daughter organism is created from a growth on the parent (or bud). The daughter cells are smaller than the parent cells.
- e.g Hydra and yeast
Fragmentation: An organism breaks into smaller parts, which develop into new daughter organisms. The daughter organisms are smaller than the parent organisms.
- e.g. Starfish
Parthenogenesis: Also referred to as the ‘virgin birth’. The embryo can develop without fertilisation.
- e.g. Komodo dragons
compare binary fission to mitosis
state three advantages of asexual reproduction
- Can reproduce quickly
- No energy expended finding a mate
- Do not have to rely on other organisms/means to spread pollen/seeds
- Well-suited to the environment
- Able to colonise cleared areas rapidly
state two disadvantages of asexual reproduction
- Lack of genetic variation reduces the chance of a population adapting to new environmental conditions
- Pressure on the availability of resources
- If conditions change, the entire population can be lost
compare internal and external fertilisation
Internal fertilisation: union of sperm and egg occurring inside the body of the female parent
External fertilisation: union of sperm and egg occurring outside the body of the female parent
state advantages of sexual reproduction
- Genetic diversity within the species
- Variation increases survival chances should conditions change
- Variation between members of the same family due to crossing over and independent assortment during meiosis
- More traits to select for when choosing a mate — allow natural selection to occur
state disadvantages of sexual reproduction
- Energy expended to find a mate
- Some organisms can be injured (or killed) in competition for a mate
explain the importance of variation
Variation allows for natural selection to occur, with those most suited to the environment being selected to mate with
define the term clone
groups of cells, organisms or genes with identical genetic makeup
describe one method of cloning plants
Plant tissue culture: technique used to clone plants in large numbers — in the laboratory, many identical copies of a plant can be produced starting from a small amount of tissue from one plant
describe two methods of producing animal clones
Embryo splitting: process of separating the totipotent cells of a very early embryo, so that the resultant cells are each able to form a complete embryo
Somatic cell nuclear transfer: a cloning technique that involves the nucleus of a somatic cell being transferred into the cytoplasm of an enucleated cell that is then stimulated to divide
what are the benefits of cloning for farmers?
- SCNT has the potential to be an important process in animal agricultural industries due to the opportunity to select traits that can enhance agricultural yields
- It has the potential to save the genetic information of species facing extinction
