Reproduction and Inheritance Flashcards
What is the difference between sexual and asexual production?
1) sex cells have to be produced for sexual reproduction but not asexual
2) fertilisation takes place in sexual reproduction but not asexual
3) sexual reproduction produces variation amongst offspring
4) sexual reproduction has survival in a changing environment and asexual in a stable environment
What is involved in fertilisation?
The fusion of a male and female gamete to produce a zygote which undergoes cell division and develops into an embryo
By which natural methods can plants reproduce asexually?
1) runners (side shoot grown from parent plant and a new plant is produced where the runner touches the ground)
2) tubers (food stores which form underground at the end of branches and several plants can grow from each tuber)
3) bulbs (plants send nutrients from photosynthesis down to the bulb until it becomes so swollen that it splits into multiple bulbs)
how are insect pollinated plants adapted for pollination?
1) stamen are enclosed within the flower so the insect must make contact
2) stigma is enclosed within the flower so that the insect must make contact
3) stigma is sticky so pollen grains attach from insects
4) petals are large and brightly coloured to attract insects
5) pollen grains are large and sticky in order to attach to insects’ bodies
6) nectaries are present
what is meant by the term pollination?
the transfer of pollen from the anther to the stigma
what is the cross pollination?
when pollen from a different plant is transferred to the stigma, which promotes variation
what is self pollination?
when pollen from the same plant is transferred to the stigma
how are wind pollinated plants adapted for pollination?
1) stamen are exposed so wind can easily blow pollen away
2) stigma is exposed to catch pollen grains blowing in the wind
3) stigma is feather in order to catch pollen grains
4) pollen grains are smooth and inflated in order to be easily carried in the wind
describe the process of fertilisation in plants?
1) Pollen grain lands on stigma
2) Pollen grain grows a pollen tube down the style into the ovule
3) Pollen grain nucleus moves down the tube from the pollen grain and it fuses with the female gamete (the nucleus of the ovum) to form a zygote
what does fertilisation lead to?
seed and fruit formation
why do seeds need to be dispersed away from the parent plant?
in order to reduce competition for light, nutrients and water
give examples of male secondary sexual characteristics
1) growth of facial and body hair
2) muscle development
3) voice breaking
give examples of female secondary sexual characteristics
1) breast development
2) beginning of menstruation
3) growth of body and pubic hair
what occurs at puberty other than the development of secondary sexual characteristics?
sex cells (eggs and sperm) start to be produced
what is the role of oestrogen in the menstrual cycle?
1) stimulates the lining of the uterus to thicken
2) reduces levels of FSH
3) increases levels of LH
what is the role of progesterone in the menstrual cycle?
stimulates the growth of blood vessels in the lining of the uterus, preparing for pregnancy, and if a fertilised ovum arrives in the corpus luteum continues producing progesterone maintains the uterus lining and stops ovulation occuring
describe fertilisation in humans?
1) Gametes (sperm and ova) are produced in the sex organs (testes and ovaries)
2) Once sperm are deposited in the vagina during sexual intercourse, they swim towards the ovum using their specialised tails (flagellum)
3) Once one sperm penetrates the ovum cell membrame, an extra membrane (the fertilisation membrane) prevents any more sperm form entering
4) The sperm nucleus fuses with the ovum nucleus forming a zygote which divides by mitosis to become a foetus
Given that the number of chromosomes in gametes are less than those in normal cells how are the number of chromosomes in animals maintained in their offspring?
1) meiosis
2) gametes
3) haploid
4) fertilisation/ fuse
5) diploid
Describe the changes that take place in the uterus during the menstrual cycle
1) grows/thickens
2) maintained
3) breakdown/shedding
4) not broken down if pregnant
Why does the father determine the sex of the baby?
Male is XY (sperm are X or Y)
How is cell division by meiosis different to mitosis?
1) produces four cells/has two cell divisions
2) produces haploid cells
3) halves the chromosome number
4) produces genetic variation
5) produces gametes
6) takes place in sex organs
How does cutting the sperm duct prevent partner from becoming pregnant?
1) prevents sperm leaving the penis/urethra
2) no fertilisation
Why is the operation to cut the oviduct far less common than the one to cut the sperm duct?
1) testes outside
2) less invasive
3) possible to reverse
What is the bit supporting the anther in a flower called?
Filament
