Inheritance, Variation and Evolution Flashcards
what is meiosis
the formation of four non identical cells from one cell
what is mitosis
the formation of two identical cells from one cell
what is sexual reproduction
the joining of male and female gametes, each containing genetic information from the mother or father
what are the gametes in animals
sperm and egg cells
what are the gametes in flowering plants
pollen and egg cells
how are gametes formed
meiosis
how do we know gametes are formed by meiosis
they are non identical
how many chromosomes does a normal cell have
46 chromosomes
how many chromosomes do gametes ahve
23 chromosomes
when do the gametes chromosomes fuse
fertilisation
what happens when gametes fuse
genetic information from each parent is mixed producing variation in the offspring
what is asexual reproduction
one parent with no gametes joining
how does asexual reproduction happen
mitosis
what does asexual reproduction lead to
clones that are genetically identical to eachother and the parent
examples of organisms produced by asexual reproduction
bacteria
some plants
some animals
process of meiosis
cell makes copies of its chromosomes so it has double the genetic information
the cell divides into two cells each with half the amount of chromosomes
the cell divides again predicting four cells each with a quarter of the amount of chromosomes
these cells are called gametes and are genetically different from eachother
why are gametes genetically different from eachother
the chromosomes are shuffled during the process resulting in random chromosomes ending up in each of the four cells
what happens during fertilisation of gametes
fuse and produce a cell with 46 chromosomes
this cell divides by mitosis to produce many copies
more and more cells are produced and an embryo forms
the cells are differentiated and take on different roles after this stage
advantages of sexual reproduction
produces variation in offspring
allows us to use selective breeding
advantages of asexual reproduction
only one parent is needed
uses less energy and is faster as organisms do not need to find a mate
in favorable conditions lots of identical offspring can be produced
why is producing variation in offspring an advantage
if the environment changes an organism of the species will have a characteristic that gives them a survival advantage
decreases the chance of the whole species becoming extinct
why is selective breeding an advantage of sexual reproduction
organisms with desirable characteristics can be bred
speeds up natural selection
which organisms use asexual and sexual reproduction to reproduce
malarial parasites
some fungi
some plants
how do malarial parasites use s and a reproduction
reproduce sexually in the mosquito
reproduce asexuallly in the human host in the liver and blood cells