reproduction and inheritance (topic 3) Flashcards
fertilisation
invloves the fusion of male and female gamete to produce a zygote that undergoes cell division and develops into an embryo
insect pollinated petals
large and bright to attract insects
wind pollinated petals
small and dull - usally green or brown
insect pollinated nectar
scented with nectar to attract insects
wind pollinated nectar
no scent or nectar
wind pollinated pollen grains
smooth, light so they can easily be carried by the wind and in large amounts to ensure some reach other flowers.
insect pollinated pollen grains
sticky and in moderate amounts
insect pollinated anthers
inside flower, stiff and attached so that insects can brush past
insect pollinated stigma
inside flower, sticky so pollen grains stick to it when an insect brushes past
wind pollinated stigma
outside flower, feather so forms network to catch pollen grains drifting in the wind
wind pollinated anthers
outside flower, loose on long filaments so that pollen can be released easily
ovule
female gamete in plants
pollen grains
male gamete in plans
embryo
young root and shoot, becomes the adult plant
food store
starch for the plant to use until its able to carry out photosynthesis
seed coat
a protective covering
how long does the menstural cycle last?
on what day is the egg released?
lasts 28 days, egg is released on day 14 (ovulation)
oestrogen
Causes thickening of the uterus in preperation for inplantation of an egg. Levels peak on day 10 and then begin to fall.
progesterone
Maintains thick lining of uterus. Inhibits release of LH and FSH. The egg matures on day 14 and progesterone starts increasing after this until it reaches its peak 3 days later. If eggs not fertilised progesterone levels fall and the uterus lining breaks down in a period lasting for around 5 days.
Secondary sexual characterises
Female - oestrogen
- breast development
- widening of hips
- menstural cycle begins
- body hair growth
- height increase
Secondary sexual characteristics
Males - testosterone
- voice lowering/breaking
- production of sperm
- growth of facial/body hair
- muscle development
- growth of penis/testes
amniotic fluid
liquid contained in a bag (amnion) in the uterus that surrounds the foetus. It protects the foetus and cushions any rough movement. When labour begins the amnion breaks and the fluid comes out - often known as a womens ‘water breaking’
gamete
An organisms reproductive cell (egg in females, sperm in males) which has half the number of chromosomes (23)
genome
The entire dna of an organism
chromosome
Structure found in the necleus which is made up of a long strand of DNA.
genetic variation
difference in DNA sequences of indivduals within the same species
mutations
rare, random change in genetic material that can be inerhited
enviromental variation
caused by differences in lifestyle, diet, climate etc, which could lead to organisms adapting.
genetic variation
eye colour, blood type etc, as these phenotypes are dependent on inheriting alleles from parents.
give an example of genetic and environment variation interaction
height, a child may have potential to grow tall due to genetics but if their malnourished then they may not grow as much
random fertilisation
increaeses genetic variation
sperm duct
male
sperm passes through this
sex gland
male
produces semen that contains sperm cells
testis
male
contained in scrotum (bag of skin) and produces sperm and testosterone
penis
male
passes urine and semen out of the body
urethra
male
tube inside penise to carry urine/semen, a ring of muscle inside stops the two mixing.
ovary
contains ova (female gametes) which develop when FSH is released
vagina
muscular tube that leads to the inside of the body
uterus
has a thick lining so that fertilised eggs can be implanted
cervix
ring of muscle at lower end of uterus to ensure foetus remains in place during pregnancy
oviduct
connects ovary to the uterus and is lined with ciliated cells that push the ovum towards the uterus for fertilisation
gene
A short section of DNA that codes for a protein, and therefore contribute to a characteristic. Some characterists are controlled by a single genem such as fur colour in mice and red-green colour blindness in humans. However, most characteristics are the result of many different genes interacting.
allele/varient
The different forms of the gene - humans have two alleles for each gene as they inherit one from each parent.
dominant allele
Only one (out of the two alleles) is needed for it to be expressed and for the corresponding phenotype to be observed
recessive allele
Two copies are needed for it to be expressed and for the corresponding the phenotype to be observed.
homozygous
when both inherited alleles are the same (i.e. two dominant alleles or two recessive alleles)
heterozygous
when one of the inherited alleles is dominant and the other is recessive.
genotype
the combination of alleles an individual has
phenotype
the physical characteristics that are observed in the individual e.g eye colour, phenotypic features are the result of polygenic (multiple genes) inheritance rather than single genes.
codominance
when neither allele is dominant over the other, so both contribute to the phenotype
FSH (follicle stimulating hormone)
causes maturation of the egg within the ovary
LH (luteinising hormone)
stimulates the release of the egg during ovulation
placenta
Allows diffusion of glucose, oxygen and amino acids from the mothers blood to the developing foetus for growth.
germination
the process in which seeds begin to develop into a new young plant
DNA stands for…
deoxyribonucleic acid
