reproduction

Question 1

define asexual production
give examples

Answer 1

a process resulting in the production of genetically identical offspring from ONE parent

e.g strawberries using runners, bacteria, tulips using bulbs, fungi spores, potato

Question 2

advantages of asexual production

Answer 2

• lots of offspring produced very quickly
  (bacteria such as e.coli divide every half hour to colonise a new area very quickly)
• no need to attract mate, less energy needed
• rapid colonisation of favorable environment –> large yields with benefical features reproduces asexually –> offspring inherit same feations –> consistent products.
• no need for pollination –> benefical in environments where scare pollinators.
• crop plants can be grown asexually from cuttings (of parent plant) plants can reach maturity quicker –> harvestation sooner.

Question 3

disadvantages of asexual production

Answer 3

• no genetic variation; organisms unlikely to adapt to changes in environemnt
• overpopulation if too many offspring produced
• parent = no resistance to disease = entire population affected

Question 4

define sexual production

Answer 4

process involving the
fusion of the nuclei of 2 gametes to form a zygote
& the production of
offspring that are genetically different form each other

Question 5

define fertilisation

Answer 5

the fusion of the nuclei of gametes

Question 6

advantages of sexual reproduction

Answer 6

• genetic variation = outbreak of disease = unlikely every individual affected
• diversity/biodiversiy = natural selection & evolution = species become better adapted to environment
• selective breeding can be used = improves crop production & quality.

Question 7

disadvantages of sexual reproduction

Answer 7

• more time & energy required to find mate = organisms produce fewer offspring in lifetime
• isolated organisms unable to reproduce sexually
• variation may lead to organisms w/o desired features
• could lead to reduced/unpredictable harvests

Question 8

state the gametes in animals & plants in both sex

Answer 8

female - plant - nucles in ovule
male - plant - pollen in anther

female - animal - egg cell
male - animal - sperm

Question 9

state the name of the male reproductive system in plants & its components

Answer 9

stamen
* anther - contains pollen grains - male gametes
* filament - holds up anther

Question 10

state the name of the female reproductive system in plants & its components

Answer 10

carpel
* stigma - pollen grains attach here/received
* style - supports stigma, connects stigma to ovary
* ovary - contains female gametes inside ovules which develop into seed after fertilisation

Question 11

define pollination

Answer 11

• tranfer of pollen grains from an anther
• to a stigma

Question 12

define self pollination

Answer 12

• transfer of pollen grains
• from the anther of a flower
• to the stigma of the same flower
• or a different flower on the same plant

Question 13

define cross pollination

Answer 13

• transfer of pollen grains
• from the anther of a flower
• to the stigma of a flower on a different plant
• of the same species

Question 14

in plants

adv & disad of self pollination

Answer 14

ad
* no need to reply on pollinators -> easier to spread in locations where pollinators scarce

disad
* less variation bc gene pool smaller. less likely to adapt to changing environment

Question 15

in plants

adv & disad of cross pollination

Answer 15

ad
* variation; more likel to changing environemnt

disad
* reliance on pollinators; pollinator population decline = harder to reproduce.

Question 16

how plants are adapted for pollination by insects

Answer 16

• petals large, brightly colored; attract insects
• scent & nectar nectaries secrete nectar. scent strong
• stigma sticky - pollen picked by insect on other plants will stick
• pollen big, sticky, spiky, stick to insects

Question 17

how plants are adapted for pollination by wind

Answer 17

• petals small, dull
• no nectaries/strong scents
• filament long, hang anthers outside flower; pollen gets blown
• stigma large, feathery to catch pollen. hangs outside flower
• pollen small, lightweight, smooth - can be easily carried to other plants by wind.

Question 18

define fertilisation in plants

Answer 18

occurs when a pollen nucleus
fueses with a nucleus in an ovule

Question 19

describe the process of fertilization in plants

Answer 19

• pollen grains lands on stigma of flower
• pollen tube grows out of pollen grain, down through the style, through micropyle, to the ovary, into the nucleus.
• nucleus from male gamete moves down tube to join with female gamete in ovule.
• fertilization happens. gametes fuse together to make zygote. divides by mitosis to form embryo.
• each ovule containing fertilizied female gamete forms a seed - can grow into new plant.

Question 20

conditions for germination

Answer 20

• water to activate enzymes breaking down food reserves in seed
• oxygen for respiration, which transfers energy from food for growth
• suitable temp for enzymes inside to work

Question 21

parts of male reproductive system and their function

Answer 21

• testes where sperm are made; contained in scrotum
• scrotum sacs - contains & supports testes
• sperm ducts muscular tube. transports sperm from testis towards urethra
• prostrate gland produces semen (provides sperm cells w nutrition)
• urethra tube. carries sperm through penis during ejaculation. urine also passes here to exit body.
• penis swells when filled w/ blood for introducing sperm into female. contains urethra.

Question 22

parts of female reproductive system and their function

Answer 22

• ovaries produces egg cells & sex hormones
• oviducts/fallopian tubes muscular tube. carries ovum from ovary to uterus.
• uterus/womb muscular w/ soft lining. fertilised egg cell implanted here to develop into fetus. protects fetus.
• cervix neck of uterus/ring of muscle at lower end of uterus. keeps fetus in place during pregnancy.
• vagina where sperm are deposited.

Question 23

definition of fertilization in humans/animals

Answer 23

fusion of the nuclei from a male gamete (sperm)
& a female gamete (egg cell)

Question 24

adaptive features of egg cell

Answer 24

• Energy stores in cytoplasm provides nutrients for zygote so it can divide faster after fertilisation & form an embryo.
• Jelly coating changes at fertilisation. after fertilisation, hardens to stop any more sperm getting in. makes sure offspring end up w/ right amount of DNA.

Question 25

adaptive features of sperm

Answer 25

• flagellum ability to swim to egg
• acrosomes (enzymes in portion of head) digests through jelly coat
• mitochondria (in middle piece) energy for flagellum to move.

Question 26

process of fertilisation & development of embryo

Answer 26

1. egg cell fertilised, now called a zygote.
2. within 4 days, zygote develops into an embryo by dividing several times; this is a ball of cells that implants into the lining of the uterus.
3. once embryo has been implanted, the placenta develops
4. placenta is connected to embryo by umbilical cord
5. embryo surrounded by amniotic sac, filled with ammniotic fluid
6. 9 weeks after fertilisation, embryo = fetus.

Question 27

what is the function of amniotic sac & fluid?

Answer 27

amniotic sac - contains amniotic fluid
amniotic fluid
* protects fetus against knocks & bumps
* support fetus as it grows
* allow fetus to move

Question 28

function of umbilical cord & placenta

Answer 28

• Umbilical cord carries substances between the fetus & placenta
• Placenta where substances are exchanged between the fetus & mother.
• provides a barrier to most toxins & pathogens
• some can still pass across the placenta & into the fetus, affecting the fetus.