10 Reproduction Flashcards
Define asexual reproduction
process resulting in the production of genetically identical offspring from one parent
Advantages of asexual reproduction (3)
Only one parent required
large number of organisms can be produced in a short time
offsprings are identical, so should survive well in the conditions in which parents grow
Disadvantages of asexual reproduction (2)
Lack of variation means that any adverse change in conditions will affect all
offsprings do not vary so they are not suited to moving away and exploiting environments with different conditions
What is a gamete
sex cell
Define sexual reproduction
process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offsprings that are genetically different from each other
is gamete haploid or diploid
haploid
Is zygote haploid or diploid
diploid
Advantages of sexual reproduction
Variety in offsprings
- produce individuals that may be better adpated to different conditions, increasing chance of survival of species
Disadvantages of sexual reproduction (2)
requires second parent for fertilisation
The need to find a mate means that sexual reproduction takes longer to produce offspring than asexual
What is fertilisation
nucelus of a male gamete fuses with the nucelus of a female gamete to form a zygote
The functions of the key parts of an insect-pollinated flower (5)
sepal - help to protect the growing flower and stop it from drying out
petal - brightly coloured to attract insects and animals to pollinate the plant
Anther - produces plant gametes (pollen)
Stigma - covered in a sticky, waxy layer that traps the pollen of other plants.
Ovary - contains an ovule (a gamete)
What are the male parts of a flower called and what do they contain
Collevtively called Stamen
contains an anther and filament
What are the female parts of a flower called and what do they contain
Collectively called Carpel
contains the stigma, style, and the ovary
Define pollination
transfer of pollen grains from the anther to the stigma
Features of wind - pollinated plants (9)
Small petal - to not obstruct pollen dispersal
inconspicuous petals
no scent
no nectaries
many anthers which are often large and hang outside the flower so that pollen is easily dispersed
pollen grains have smooth outer walls
stigmas are large and feathery, often hang outside the flower to trap pollen
produce large amounts of pollen
pollen is lightweight
Features of insect - pollinated plants (9)
large petals for insects to land on
brightly coloured petals to attract insects
often scented to attract insects
nectaries present at the base of the flower produce a sugary liquid to attract insects
a few small anthers, usually held inside the flower
pollen grains have sticky or spiky outer walls
stigmas are small and held inside the flower
produce smaller amounts of pollen
pollen is heavier
When does fertilisation in plants occur
when a pollen nucleus fuses with a nucleus in an ovule
Define germination
when the seed coat breaks open and the embryo starts to grow and develop into a new plant
What are the 3 environmental conditions needed for successful germination (3)
Temperature
Water - Swell seed and burst seed coat
Oxygen - respiration
What is more water needed for during germination (4)
Activation of hormones an enzymes
hydrolysis of storage compounds, eg: conversion of starch to glucose
Transport of materials to be used for respiration and growth
Metabolic reactions and enzyme actions that occur in solution
Where is sperm produced
tesetes
Why are the testes supported outside the body in the scrotum (2)
Keep tests cool
at high temperatures, fewer sperm are produced
Purpose of sperm duct
carry sperm from the testes to the penis
Purpose of prostate gland and seminal vesicles
produce liquid called semen
Purpose of of semen
fluid that allow sperm to swim in
Define urethra
A tube that allows the passage of semen and urine through the centre of the penis.
Explain the pathway of sperm
Sperm produce in testicles —-> go up sperm duct —> receive fluid from seminal vesicle and prostate gland, creating a mixture called semen —> go out the urethra
Which female organ produces the eggs
ovaries
Define penis
transfers semen to vagina during sexual intercourse
Define oviducts
transfers egg to uterus and the site of fertilisation
Define uterus
where the fetus develops
Define cervix (2)
ring of muscle at the opening of the uterus
Produces mucus which changes during menstrual cycle, allowing sperm to pass through at some times and not others
Define vagina
receives penis during sexual
intercourse
Features of sperm (4)
Contains a small sac of enzymes called the acrosome
Contains nucleus for DNA
contains flagellum to beat back and forth to move the sperm cell
contains mitochondria to provide energy from respiration for flagellum movement
How does the egg cell move
wafted along the oviduct by cilia
Features of egg cell
nucleus
cytoplasm
Jelly coat
Purpose of cytoplasm in egg cell
provides nutrients for the dividing zygote after fertilisation
What does the jelly coat in the egg cell do
protects the egg celll
What does jelly coat do after fertilisation in egg cell
After fertilisation by one sperm, the jelly coat changes to an impenetrable barrier
Define ovulation
phase of the female menstrual cycle that involves the release of an egg (ovum) from one of the ovaries.
Where does fertilisation take place
oviduct
Where does the fertilised egg (zygote) travel to
uterus
Describe the early development of the fetus (3)
zygote divide several times to form a ball of 64 cells, known as an embryo
In the uterus, the embryo embeds in the thickened lining (implantation) and cell division and growth continues
For the first three months, the embryo gets nutrients from mother by diffusion through the uterus lining
Where does the fetus develop
in a bag of fluid called amniotic fluid inside the uterus
Where is the amniotic fluid produced
produced from amniotic membrane that forms the outer layer of the amniotic sac
Purpose of amniotic fluid (2)
mechanical damage
reduces effect the effect of large temperature variations that would affect the rate of development of the fetus
When does birth occur
When all the organs of the fetus are fully developed
Purpose of placenta
allows exchange of materials between the mother and fetus
Purpose of umbilical cord
carries blood vessels of the fetus
Joins fetus to the placenta
Reasons for the structure of placenta (2)
Placenta and uterus run close to each other but do not touch. Materials and fetal blood do not mix. If they did the higher blood pressure in the mother could damage the fetus
Prevent pathogens and some chemicals getting into the blood of the fetus. Some pathogens like nicotine are small enough to cross through placenta
How does fetus get Dissolved food molecules, oxygen, and other nutrients needed for growth
diffuses from the mother’s blood into the blood of the fetus
How are waste products from metabolism disposed
fetus’s blood diffuse across into the mother’s blood
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