P1 3a reproduction Flashcards
what is the function of the testes?
produce the hormone testosterone
produce sperm cells
what is the function of the epididymis?
the sperm cells go into the epididymis and mature, they are stored in there
what is the function of the sperm duct?
transfer the semen during ejaculation
what is the function of the seminal vesicle?
it produces semen, which is a sugary solution
what is the function of the prostate?
produces the rest of the semen and anticoagulants
- there are also Chemicals in the prostate (that get mixed in with semen) that stop the semen from denaturing from the strong acids in the vagina
what is the function of erectile tissue?
it acts like a sponge and fills up and absorbs with blood, creates high pressure
what does mitochondria do?
provides energy through anaerobic respiration
what is the function of the ovaries?
produce egg cells, or the ova
where two hormones are made, progesterone and oestrogen
what is the function of the Fallopian tubes?
bring the egg cells into the uterus
- it has Sicilia in it which moves the eggs along, this can take about 7 days
where does fertilisation happen?
in the fallopian tubes
what happens in fertilisation?
the egg cells goes into the uterus and grows, the endometrium layer provides it with minerals, nutrients etc
what happens if the egg cell doesn’t get fertilised?
the endometrium layer and the egg cell sheds, which is menustrating
what is the function of the cervix?
supports the growing embryo in the uterus, can contract and relax
- closes for support
what is the function of the vagina?
connects the Cervix and uterus
is it where sperm enters the body
what is sexual reproduction?
the process involving the fusion of the nuclei of two gametes, that from a zygote
- it is the production of offspring that are genetically different from each other
what is fertilisation?
fusion of gamete nuclei
what makes gametes different?
they are haploid nucleus, they contain 23 chromosomes
what are the advantages for sexual reproduction?
- increases genetic variation
- can adapt to new environments due to reproduction, gives survival advantage
- disease is less likely to affect a whole population (again due to variation)
what are the disadvantages for sexual reproduction?
- take time and energy to find mates
- difficult for isolated members of the species to reproduce
what is asexual reproduction?
the process resulting in genetically identical offspring being produced from one parent
what makes asexual reproduction different?
- doesn’t involve gametes or fertilisation
- only one parent is required
- no genetic variation, the offspring is genetically identical to the parent
what is the process of bacteria reproducing called?
binary fission
what is the process of binary fission?
cell contents double
cell division by binary fission
produced two genetically identical daughter cells
what are the advantages of asexual reproduction?
- population can be increased rapidly when conditions are right
- can exploit suitable environments quickly
- more time and energy efficient
- its completed much faster
what are the disadvantages of asexual reproduction?
- limited genetic variation in population
- population is vulnerable to changes in conditions, Amy only be suited to one environment/habitat
- disease is likely to effect whole population (no variation)
what is pollination?
the transfer of pollen grains from an anther to a stigma
what are the two types of pollination?
- insect-pollinated flowers
- wind pollinated flowers
what is the function of the sepal?
protects the unopened flower
what is the function of the petals?
brightly coloured in insect pollinated flowers to attract insects
what is the function of the anther?
produces and released the male sex cell (pollen grain)
what is the function of the stigma?
top of the female part of the flower which collets pollen grains
what is the function of the ovary?
produces the female sex cell (ovum)
what is the function of the ovule?
contains the female sex cell, found inside the ovary
what happens in insect pollinated flowers?
pollinating agents are insects
- incests visit flower to collect nectar
- it brushes against the anthers and they deposit sticky pollen onto the insects body
- when the insect goes to another flower some of the pollen gets deposited onto the stigma of the second flower
what are the adaptations to insect pollinated flowers?
- large brightly coloured petals
- strong scent and nectar to attract insects
- moderate amount of pollen grains
- pollen grains are large and sticky
- anthers are inside flowers, firmly attached
- stigma are inside flower, sticky
what happens in wind pollination?
- anthers open and shed their pollen
- pollen is blown or carried by the wind, until by chance it lands on the stigma of the same plant species
what are the adaptations to wind pollinated flowers?
- petals are small and dull
- no scent or nectar present
- large amounts of pollen grains
- polen is smooth, small and light
- anthers and stigma are outside the flower, to release and catch pollen grains
what is cross pollination?
- when pollen from one plant is transferred to the stigma of another plant of the same species
advantage of cross pollination?
Increases the genetic variation in the offspring
what is self pollination?
when pollen lands on its own stigma, or it lands on the stigma of another flower on the same plant
when does fertilisation occur in plants?
when the pollen grain nucleus fuses with the ovum nucleus
what happens in plant fertilisation?
- pollen grain lands of stigma
- pollen tube begins to grow down style
- pollen nucleus travels down pollen tube
- pollen tube enters ovule through micropyle
- pollen nucleus fuses with ovum nucleus
- ovule eventually develops into a seed
how do seeds from?
the ovule, containing the zygote develops into the seed
- the wall develops into the seed coat
how does fruit form?
the ovary walls, or the parts around the ovule develop into fruit
why are fruit produced and helpful to plants?
- provide a mechanism for seed dispersal
what is germination?
start of growth in the seed
what happens in germination?
the embryo begins to grow into the seedling
- the cotyledons provide food and therefore energy when the seed starts germinating
- when the seedling grows leaves it becomes capable of making its own food through photosynthesis
- after taking in water the seed coat splits
practical, conditions for germination
- set up 4 test tubes, contains 10 cress seeds on cotton wool
- for test tube A leave wool dry
- for B add enough water to cotton so it becomes moist
- for C add water to cover wool and seeds, add layer of oil
- for D add enough that its moist
- leave A,B,C at room temp
- D in fridge
leave tubes for 3 days (add more water if needed)
what are the factors required for successful germination?
- water
- oxygen
- warmth/sun
how does natural asexual reproduction in plants happen?
- some plants grow runners that have small platelets at the ends
- grow sideways
- when they touch the soil the platelets will grow roots
how does artificial asexual reproduction in plants happen?
taking cuttings
- a section with a new bud is cut off
- can be placed in water or directly into soil
- rooting powder, contains rooting hormones can be used to encourage new growths
what is the function of the scrotum?
sac supporting testes to ensure sperm are kept at the same temperature
what is the function of the penis?
passes urine and allows semen to pass into vagina
what are the parts of the sperm?
acrosome - head
tail
middle piece
what are the adaptive features of sperm?
flagellum - till
contains enzymes (in acrosome)
has lots of mitochondria
what are the parts of the egg cells?
cytoplasm, haploid nucleus, cell membrane, mitochondria
what are the adaptive features of egg cells?
cytoplasm contains a store of energy
jelly like coating that changes after fertilisation
why does the sperm have flagellum?
enables it to swim to the egg
why does the sperm have enzymes in the acrosome?
to digest through jelly coat and cell membrane of an egg cell
why does the sperm have mitochondria?
provides energy from respiration, for locomotion q
why does the egg cell have cytoplasm with a store of energy?
provides energy for the diving zygote after fertilisation
why does the egg cell have a jelly like coating?
forms an impenetrable barrier after fertilisation to prevent other sperm entering the egg cell
what happens in fertilisation?
when a sperm meets an egg cell in the oviduct, fertilisation can occur
- it is the fusion of the nuclei from a male gamete and a female gamete
- during it the head of the sperm releases enzymes that digest a path though the protective layer of the cell
- then the egg cell releases a thick layer of material that prevents any more sperm from entering
what happens after fusion of the gametes?
they become a zygote, which then divides by mitosis to form two new cells, this continues until an embryo is formed
what happens during ejaculation?
millions of sperm cell move along the sperm duct
they are suspended in semen
the semen passes into the urethra
- when the sperm travels through the plug of mucus in the cervix to reach the uterus
what happens in implantation of the foetus?
the embryo will reach the uterus and embeds itself in the thick lining, where it will continue to grow and develop
where does the placenta form?
where the embryo is attached
what is placenta?
an organ that ensures materials can be exchanged between the blood of the mother and the growing embryo
what is the umbilical cord?
it joins the embryos blood supply to the placenta for exchange of nutrients and removal of waste products
what is amniotic fluid?
a fluid made from the mothers blood plasma
- its held in the amniotic sac
what does amniotic fluid do?
protects the embryo during development
what does the mothers blood absorb from the foetus blood in the placenta?
carbon dioxide and urea
what does the foetus need to grow, and where does it get it?
glucose, amino acids, fatty acids, water, oxygen, mineral ions and vitamins
from the mother through the umbilical cord
how is the placenta adapted?
large surface area and thin wall for efficient diffusion
what are the effects of oestrogen?
female hormone that develop secondary sexual characteristics
- breast develop
- body hair grows
- menstrual cycle begins
- hips get wider
what are the effects of testosterone?
male hormone that develop secondary sexual characteristics
- growth of penis and testes
- growth of facial and body hair
- muscles develop
- voice breaks
- testes start to produce sperm
what is the role of progesterone in the menstrual cycle?
- maintains and thickens the lining of the uterus
- if fertilisation doesn’t occur levels drop and mensturation occurs
what is the role of oestrogen in the menstrual cycle?
- stimulates the uterus to develop a lining
