Topic 3 - Reproduction Flashcards
What is sexual reproduction?
● Type of reproduction
● Involves the production of gametes by meiosis
● A gamete from each parent fuses to form a zygote
● Genetic information from each gamete is mixed so the resulting zygote is unique
What are gametes?
What are gametes?
● Sex cells (sperm cells, egg cells)
● Haploid (half the number of chromosomes)
What is meiosis?
● Form of cell division involved in the formation of
gametes
● Chromosome number is halved
● Involves two divisions
What must occur prior to meiosis?
Interphase
What happens during the first stage of meiosis?
● Chromosome pairs line up along the cell equator
● The pair of chromosomes are separated and move to
opposite poles of the cell (the side to which each
chromosome is pulled is random, creating variation)
● Chromosome number is halved
What happens during the second stage
of meiosis?
● Chromosomes line up along the cell equator
● The chromatids are separated and move to opposite
poles of the cell
● Four unique haploid gametes are produced
Why is meiosis important for sexual reproduction?
● It increases genetic variation
● It ensures that the resultant zygote is
diploid
What is the advantage of sexual reproduction?
It creates genetic variation, increasing the probability of a species adapting to and surviving environmental changes.
Describe the disadvantages of sexual reproduction
● Two parents are required. This makes reproduction
difficult in endangered populations or in species which
exhibit solitary lifestyles
● More time and energy is required so fewer offspring
are produced
What is asexual reproduction?
● Type of reproduction
● Involves mitosis
● Produces genetically identical offspring
known as daughter cells
Describe the advantages of asexual reproduction
● Only one parent is required
● Lots of offspring can be produced in a short period of time, enabling the rapid colonisation of an area and
reducing competition from other species
● Requires less energy
What is the disadvantage of asexual reproduction?
No genetic variation (except from spontaneous mutations) reducing the
probability of a species being able to adapt to environmental change
