16. Reproduction Flashcards
what is asexual reproduction
the production of two genetically identical offspring from one parent
give one advantage and one disadvantage of asexual reproduction
advantage - it produces lots of offsprings quickly
disadvantage - it does not introduce variation and so all offsprings are susceptible to the same environmental pressures as the parents
what is sexual reproduction
the production of two genetically different offspring from the fusion of the nuclei from two gametes
define fertilisation
the fusion of the nuclei from two gametes
state the difference in the number of chromosomes in a gamete nucleus compared with a zygote nucleus
gametes have a haploid nucleus (23 chromosomes) whereas zygotes have a dipole nuclei (23 pairs of chromosomes)
give one advantage and one disadvantage of sexual reproduction
advantage - it introduces variation
disadvantage - it is slower and produces a limited amount of offspring
label the insect pollinated flower below
what is the function of the sepals in a plant insect pollinated plant
the sepal is a hard coating that protects the developing flower in a bud
what is the function of the petals in an insect pollinated plant
the petals attract the insects so that they can pollinate the plant
what is the function of the anthers in an insect pollinated plant
the anthers contain the pollen sacs which contain the male sex cells of the plant
what is the function of the stigma in an insect pollinated plant
these are sticky parts of the plant designed to capture the pollen grains
what is the function of the ovaries in an insect pollinated plant
they contain ovules which will grow into seeds when they are fertilized by pollen
label the diagram of a wind pollinated plant below
a - stigma
b - anthers
what type of pollen grain is this and why
pollen from an insect pollinated as it has spikes on it to make it sticky to be picked up by insects
what type of pollen grain is this and why
pollen from a wind pollinated as it is smooth so that it can be carried by the wind easily
what is pollination
where pollen grains are transferred from the anthers to the stigma
what is self pollination
where pollen grains are transferred from the anthers to th stigma of the same plant
what is cross pollination
where pollen grains are transferred from the anthers of one plant to the stigma of another plant of the same species
give one advantage of self pollination
there is a greater chance of fertilization as it does not rely on pollinators
give one disadvantage of self pollination
genetic variation decreases and the plant is less able to adapt to the environment
give one advantage of cross pollination
the plants are more able to adapt environmental changes and there is increased genetic variation
give one disadvantage of cross pollination
the plants are reliant on insect population for fertilisation
describe what happens when a pollen grain lands on the stigma of a plant
- a pollen tube grows through the style to reach the ovule in the ovary
- the nucleus from the pollen grain then travels down the pollen tube to reach the ovule
when does fertilization occur
when the nucleus of a pollen grain fuses with the nucleus of an ovule
state 3 environmental conditions that affect see germination
oxygen availability
water availability
a suitable temperature
label the following diagram of the male reproductive system
state 2 functions of the testes
they produce hormones
they produce sperm
state 2 functions of the penis
used as the male sex organ
used as an excretory organ
state 2 functions of the male urethra
- it allows urine to exit the body from the bladder
- it is used during ejaculation to release semen
state the function of the scrotum
it holds and protects the testes
state the function of the sperm duct
it carries sperm from the testes to the urethra
state the function of the prostate gland
it produces prostate fluid which combines with sperm cells to make sperm
label the following diagram of the female reproductive system
state 2 functions of the ovaries
- they produce eggs
- they produce hormones
state 2 functions of the vagina
- to receive the penis during intercourse
- it is used as the birth canal during childbirth
state the function of the oviduct
to create a passage between the ovary and the uterus for the egg to travel down
state 2 functions of the cervix
- to allow menstrual blood to flow out of the vagina
- to channel the sperm into the uterus
define fertilisation (humans)
the fusion of the nucleus of a male gamete with the nucleus of a female gamete
compare sperm and egg cells in terms of size
sperm cells are significantly smaller than egg cells
compare sperm and egg cells in terms of structure and shape
sperm cells are long and thin with a head and tail whereas egg cells are large and in the shape of a sphere or ovoid
compare sperm and egg cells in term of their ability to move
- sperm cells have large energy stores and a long tail to help them to move quickly
- egg cells do not have this and so are relatively non motile
compare sperm and egg cells in terms of number of each cell
there are many more sperm cells than egg cells
state 2 adaptive features of sperm cells
- long flagellum
- contain enzymes
explain 3 adaptive features of sperm cells
- lots of mitochondria in the middle section provide energy for movement
- enzymes in the acrosome break down he outer membrane of the egg
- long whip like flagellum used for movement
explain the 2 adaptive features of egg cell
- large energy stores allow for lots of cell divisions and growth
- jelly like coat ensures that only one sperm can fertilize the egg as it changes after fertilisation
briefly describe the early development of an embryo
- after fertilisation a zygote is formed
- the zygote implants in the uterus wall and becomes an embryo
what is the function of the umbilical cord
- it delivers oxygenated blood and nutrients to the developing foetus
- it removes deoxygenated blood and waste products from the developing foetus
what is the function of the placenta
- it separates the mother’s blood supply from the foetus blood supply
- it also allows for exchange between the mother and foetus
what is the function of the placenta
- to allow the removal of waste gases and excretory products from the foetus
- to act as a barrier for toxins and pathogens
- to provide the foetus with dissolved nutrients
what is the function of the amniotic sac and amniotic fuluid
they help to protect the developing foetus
describe the growth of the fetus over time
- the foetus begins by developing and becoming more complex
- in the later stages of pregnancy, the foetus increases in size
how can certain toxins and pathogens be harmful to the developing foetus
the toxins and pathogens can pass across the placenta and can damage the foetus
name one toxin that can affect a devolping foetus
nicotine found in cigarette smoke
name one pathogen that can affect a developing foetus
the rubella virus
describe how women should control their diet during pregnancy
- avoid smoking or drinking as this can damage the foetus
- make sure to have a balanced diet with a focus on nutrients like iron for the development of blood and calcium for the development of bones
state one advantage of breastfeeding over bottle feeding using formula milk
breastfeeding provides the child with important antibodies from the mother which proves protection against disease
state one disadvantage of breastfeeding over bottle feeding using formula milk
breastfeeding may be painful for the mother
state one advantage of bottle feeding using formula milk over breastfeeding
the other does not need to control her diet to provide the correct nutrients to her baby
state one advantage of bottle feeding using formula milk over breastfeeding
bottle feeding can be extra expense for parents
state the 6 main stage of labour and birth
- the amniotic sac breaks
- the muscles in the wall of the uterus contract
- widening of the cervix opening
- passage of the baby through the vagina
- tying and cutting the umbilical cord
- delivery of the afterbirth
what role does testosterone play during puberty
- triggers growth and development of the penis and testes
- causes the voice to deepen
- triggers the growth of pubic hair
- increases muscle mass
what role does estrogen play during puberty
- increases breast size
- triggers the development of the uterus
- it causes eggs to mature during the menstrual cycle
where iso estrogen secreted from
the ovaries
where is progesterone secreted from
the ovaries
what happens day 1-4 of the menstrual cycle
the uterus lining is shed during menstruation
what happens on day 4-14 of the menstrual cycle
the uterus lining then begins to grow again in preparation to receive an egg
what happens on day 14 of the menstrual cycle
an egg is released
what happens on day 14-28 of the menstrual cycle
the lining of the uterus is maintained
what odes follicle stimulating hormone do
FSH stimulates the follicle to mature and release estrogen
what does luteinizing hormone do
a surge in LH causes the release of an egg from a follicle
what does progesterone do
progesterone maintains the womb lining
what hormones does progesterone inhibit
progesterone inhibits follicle stimulating hormone(FSH) and luteinizing hormone (LH)
how doe estrogen pills work to prevent pregnancy
estrogen pills inhibit FSH which stops the egg from maturing
how doe progesterone pills work to prevent pregnancy
progesterone pills cause a sticky muques to form at the cervix which prevents the sperm from fertilizing the egg
give 4 different types of birth control
- natural methods
- barriers
- chemicals
- surgical methods
give 2 examples of natural methods of birth control
- abstinence
- monitoring temperature and cervical mucus levels to predict ovulation
give 2 examples of barriers that act as birth control
condoms - can be male or female condoms and prevent the sperm from entering the vagina
diaphragm - a silicone dome shaped object that is inserted into the vaigna to cover the cerivx
give 5 examples of chemical methods of birth control
- IUD
- IUS
- contraceptive pill
- implant
- injection
briefly describe the use of an IUD as a contraceptive device
IUDs are small copper-coated tubes in a T shape that prevent sperm from reaching the egg and the copper works to kill the sperm
describe the use of an IUS as a contraceptive device
- intrauterine systems are very similar to inauterine devices except they release progesterone instead of copper
- they thicken the cervical mucus and thin the worm lining
describe the use of an implant device as a contraceptive device
- the implant is a small matchstick sized device
- inserted into the upper arm
- it releases progestogen into the bloodstream which prevents ovulation
how does the contraceptive pill work
- it contains artificial versions of estrogen and progesterone which prevent pregnancy
- prevents ovulation
- thicken mucus
- alters womb lining
how does the contraceptive injection prevent pregnancy
it releases progesterone into the blood stream which prevents ovulation
state 2 surgical methods of contraception
- vasectomy
- female sterilisation
how does a vasectomy work to prevent pregnancy
the vas deferent are cut or tied which prevents sperm from being released form the testicles into the urethra
how does female sterilisation work
- the Fallopian tubes are blocked by clips or rings or they are cut
- this prevents the release of an egg from the ovaries
describe artificial insemination
sperm are placed within a woman’s uterus using a catheter
describe how IVF is carried out
- the mother is given FSH
- sperm from the father and eggs from the mother are collected
- the egg is fertilized in a laboratory and allowed to develop into an embryo
- the embryo is then put into the mother’s uterus
define STI
an infection caused by a pathogen that is transmitted through bodily fluids
give an example of an STI
HIV
state 3 ways of preventing the spread of STIs
- wearing condoms during sex
- education
don’t share needles
how is HIV spread
through bodily fluids
what can HIV infection lead to
AIDS
how does HIV affect the immune system
- decreased lymphocyte numbers
- white blood cells have a reduce ability to produce antibodies
