reproduction and development revision Flashcards
what is sexual reproduction?
the recombination of genetic material from two parents to produce genetically unique offspring that are different from both parents
what is asexual reproduction?
the copying and division of one parent cell and it’s genetic material to produce offspring that are identical to their parents and each other
why is sexual reproduction useful for?
it’s useful because genetic material is reshuffles the DNA of the new organism through fertilisation. this increases variation which is essential for evolution.
why is asexual reproduction useful?
it’s very fast and it makes use of a genetic pattern known to be able to survive the current conditions.
what is fertilisation?
fertilisation happens when the nucleus of a sperm cell fuses with the nucleus of an egg cell, taking two gamete’s and forming a zygote.
what is a zygote?
a zygote is a fertilised egg cell which is formed when a egg gamete fuses with a sperm gamete
what is a gamete?
an egg or sperm cell
what is the order of fertilisation?
female gamete nucleus + male gamete nucleus —> zygote —> embryo —> foetus —> baby
what is cell division?
cell division is the process by which new cells are made, this is how multicellular organisms grow and repair damage and how unicellular organisms reproduce
what is cell division controlled by?
the nucleus
what stages do cell division occur in?
- division of nucleus
- division of cytoplasm
what is haploid?
haploid cells only contain one set of chromosomes
what is the male gamete in plants?
pollen
what is the female gamete in plants?
ovule
what is the male gamete in animals?
sperm
what is the female gamete in animals?
egg (ova)
what does diploid mean?
diploid cells contain two sets of chromosomes, this is described as 2n
what is mitosis?
mitosis is the process by which cells divide
what are the stages of mitosis?
- chromosomes DUPLICATE themselves
- chromosomes SUPERCOIL into CHROMATIDS
- chromosomes LINE UP along the equator and spindle fibres attach to the chromosomes
- spindle fibres contract, SEPERATING the two sets of chromosomes
- nuclear membranes reform ALONG THE EQUATOR
- cytoplasm DIVIDES to form TWO IDENTICAL DAUGHTER CELLS.
what is the mitosis mnemonic?
Dont- Duplicates
Look- Lines up
Somebody’s- Separates
Dancing - Divides
what is a stem cell?
a stem cell is an unspecialised animal cell which is capable of cell division to make more cells and differentiate into other types of cells.
what are three examples of uses of stem cells?
- bone marrow transplant
- cornea transplant
- skin grafts
why are embryonic stem cells controversial?
it requires the scientists to kill the embryo and some people don’t agree with killing life for the sake of science
what are spindle fibres?
a protein material which helps separate the the chromosomes
