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biology igcse > reproduction (topic 16) > Flashcards

reproduction (topic 16) Flashcards

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1
Q

define assexual reproduction

A

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

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2
Q

outline process of assexual reproduction

A

1.bacteria dna copied
2. continued growth of cell
3.division of cell into two

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3
Q

name examples of organsims that reproduce assexually

A

bacteria, starfish, yeast, ferns, strawberry plants

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4
Q

what are advantages of assexual reproduction

A

only one parent needed (meaning faster, and saves energy)
quick reproduction
individuals offsprings are identical (good for crops, if they possess a desireable trait)

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5
Q

what are disadvtanges of assexual reproduction

A

produces identical offsprings, species is more vulnerable to changes in enviornment or diseases

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6
Q

define sexual reproduction

A

a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other

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7
Q

what are gametes

A

sex cells needed for sexual reproduction
sperm- male
egg- female

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8
Q

fertilisation

A

the fusion of the nuclei of
gametes

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9
Q

how do the nuclei of gametes compare to the nucleus of a zygote

A

gametes are haploid and zygotes are diploid

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10
Q

what is meant by diploid and haploid

A

diploid- Describes a nucleus containing two sets of chromosomes, for example in body cells. 46 chromosomes
haploid-Describes a nucleus containing a single set of unpaired chromosomes. 23 chromosomes

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11
Q

advantages of sexual reproduction

A

introduces variation, more resistant to changes in environment or to diseases
good for selective breeding

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12
Q

disadvantages of sexual reproduction

A

takes more time and energy to find a mate, more than one parent needed
much slower

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13
Q

pollination

A

The transfer of pollen grains from the anther to the stigma.

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14
Q

insect pollination what is meaning

A

Flowers that transfer their pollen by way of insect pollinators.

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15
Q

pollinators

A

Insects that transfer pollen from flower to flower in pollination.

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16
Q

name structures found in an insect pollinated flower

A

stigma, style, ovary, anther, filament, ovule, sepal, petal

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17
Q

stamen

A

male parts of the flower composed of anther and filament
to produce male gametes (pollen) and provide the correct structures and conditions necessary for the transfer of pollen

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18
Q

carpel

A

female parts of the flower composed of ovary style and stigma

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19
Q

sepal

A

green part at the top of the stem, protect the growing flower and help to stop it drying out

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20
Q

petal

A

bright coloured part, to attract insects, birds or mammals to carry out pollination

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21
Q

filament

A

stalk that supports anther, hold the anther in a position where it is able to transfer its pollen to an insect, mammal or bird

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22
Q

anther

A

powdery appearance, coloured, produce pollen grains, which contain the plant’s male gametes

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23
Q

stigma

A

usually green tallest part of the flower sticky and waxy layer, to trap pollen from other flowers

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24
Q

style

A

strucutre that supports stigma, above the ovary, to support and present the stigma in a position where it can receive pollen from an insect, bird or mammal

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25
Q

ovary

A

green, bulb-shaped part near the bottom of the flower, contains ovules (which contain the female gametes) which will develop into seeds after fertilisation

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26
Q

ovule

A

structure within the ovule, female gametes are produced and contained within the ovules. Upon fertilisation, these ovules will develop into seeds

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27
Q

pollination

A

the transfer of pollen
grains from an anther to a stigma

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28
Q

how is the pollen in insect pollinated flowers

A

spiky outer layer, larger, less pollen produced

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29
Q

how is the pollen in wind pollinated flowers

A

smooth, light, smaller, bigger production

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30
Q

self pollination

A

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

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31
Q

cross polliantion

A

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

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32
Q

what are advantgaes and disadvantages of self pollination

A

do not rely on pollinators, less energy needed, only one mate, less pollen lost however reduces variation (reducing ability to respond to changes in enviornment such as diseases)

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33
Q

what are advantgaes and disadvantages of cross pollination

A

variation increases, relies on pollinators, more energy needed, more than one mate, more pollen waisted, relies on polliantors

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34
Q

difference between petals of wind and insect pollianted flowers

A

wind- small, dull in colour, no need to attract insects,
insect- bright, large, attracts insects pollinators

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35
Q

difference between anthers of wind and insect pollianted flowers

A

wind- loosely attached and dangle outside the flower so its pollen can be blown easily by the wind
insect- located inside the flower to brush against insects

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36
Q

difference between stigma of wind and insect pollianted flowers

A

wind- loosely attached and dangle outside the flower so they can catch wind-borne pollen from other plants; often appear feathery
insect- located inside the flower to brush against insects

37
Q

what is something that insect pollinated flowers must produce but wind doesnt

A

nectar, scent

38
Q

when does fertilisation occur in plants

A

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

39
Q

describe what happens once a pollen grain is attached by the stigma

A

after pollination, pollen tube grows down style towards ovary, male gamete (sperm) move through this tube. it then reaches ovary and penetrates throguh reaching ovule, where fertilisation occurs nucleus of sperm cell fuses with nucleus of egg cell forming a zygote whcih will then develop into an embryo, eventually becoming a new plant

40
Q

germination

A

The process, controlled by enzymes, in which the seed begins to develop into a new young plant.

41
Q

what is needed for germination to occur

A

water, oxygen, suitable temp

42
Q

reproductive system

A

The organ system found in animals that is responsible for producing sperm cells or egg cells, and for producing new individuals by sexual reproduction

43
Q

what are the main structures in the male reproductive system

A

sperm duct, prostate gland, penis, urethra, testis, scrotum

44
Q

function of testes

A

organ in which sperm cells and testosterone are produced

45
Q

function of scrotum

A

sack of skin that contains the testes, helping to keep them at a slightly lower temperature than the rest of the body

46
Q

function of prostate gland

A

secretes fluid that nourishes and protects the sperm; the mixture of liquid and sperm is known as semen

47
Q

function of sperm duct

A

muscular tube that connects a testis to the urethra

48
Q

function of urethra

A

tube that allows the passage of semen and urine through the centre of the penis

49
Q

function of penis

A

during sexual intercourse, the penis is inserted into the vagina, allowing the sperm to transfer into the female reproductive system

50
Q

mains structures in female reproductive system

A

ovary, oviduct, vagina, cervix, uterus

51
Q

function of ovary

A

produces egg cells, and the hormones oestrogen and progesterone

52
Q

function of oviduct

A

tube connecting an ovary to the uterus; fertilisation usually occurs here

53
Q

function of uterus

A

organ in which the embryo develops

54
Q

function of cervix

A

ring of muscle between the vagina and the uterus

55
Q

function of vagina

A

elastic muscular canal through which the newborn passes during childbirth; during sexual intercourse, the male’s penis is inserted into the vagina

56
Q

describe fertilisation (humans)

A

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

57
Q

what are some adaptations of the sperm cell

A

tip of head has acrosome- secretes digestive enzymes allows sperm to pass through jelly coating on surface of an egg cell

flagellum- tail, allows movement

midpiece contains mitochondria- organelles release energy by respiration, which is needed to keep the flagellum moving.

58
Q

what are some adaptive features of the egg cell

A

cytoplasm contains energy stores- allow the egg to survive for several days and to nourish the zygote if fertilisation occurs, until it can implant in the wall of the uterus.

jelly coat around the egg- allows sperm to aattach, hardens to prevent polyspermy, more than one sperm fertilisation

59
Q

Compare male and female gametes in terms of:
size, structure, motility and numbers

A

male- much smaller, billions per ejaculation, move on their own
female- much larger, one released per month, cant move by their own

60
Q

what happens in early developments after fertilisation has occurred

A

zygote forms an embryo which is a ball of cells that implants into the lining of the uterus

61
Q

after eight weeks of development what is the embryo called

A

fetus

62
Q

amniotic sac

A

fetus is surrounded by a protectivelayer called the amniotic sac, A thin sac that protects the developing fetus within the uterus.

63
Q

amniotic fluid

A

The fluid that surrounds and protects the developing fetus within the amniotic sac. also contains nutrients needed bynthe fetus

64
Q

placenta

A

An organ that develops in your uterus during pregnancy, providing oxygen and nutrients and removing waste products from the developing fetus.

65
Q

main function of placenta

A

transport nutrients from mother to foetus
transport waste materials from foetus to mother

66
Q

umbilical cord

A

A cord which connects the fetus to the placenta and contains blood vessels which transport nutrients, oxygen and waste products.

67
Q

what does the placenta provide the foetus with

A

oxygen, carbohydrates, proteins, fats, vitamins, minerals and water it needs to grow

68
Q

what does the placenta receive from the foetus

A

waste materials such as carbon dioxide and urea

69
Q

how do these substances/ nutrients move from mother to foetus

A

The blood supply of the mother does not meet the blood supply of the fetus. Instead, substances diffuse through blood capillaries between the placenta and umbilical cord

70
Q

describe function of placenta in terms of protection

A

mother’s blood does not physically mix with the fetal blood supply, the placenta provides a barrier to many of the toxins and pathogens to which the mother is exposed

71
Q

what are some toxins which are able to diffuse through the placenta

A

nicotine, some pathogens eg. rubella virus

72
Q

hormone

A

A substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs.

73
Q

what are the two main hormones involved in puberty

A

testesterone- male
oestrogen- female

74
Q

what are some roles of oestrogen in secondary sexual characteristics

A

breasts develop, hair under arms, hip bones wider, pubic hairs

75
Q

what are some roles of testesterone in secondary sexual characteristics

A

facial hair, shoulders widen, hair under arms, penis and testes grow, voice deepens

76
Q

menstrual cycle

A

The monthly cycle in which an egg is released from the ovaries, and the lining of the uterus prepares for the possible implantation of a fertilised egg. If implantation does not happen, the lining breaks down and is discharged from the body, along with the unfertilised egg.

77
Q

ovulation

A

The release of a mature egg (ovum) from an ovary; it occurs approximately once every 28 days in humans. usually around day 14

78
Q

what does the follicle develop into after ovulation

A

corpus luteum

79
Q

what happens from day 4 in a menstrual cycle to the lining of the uterus

A

the lining thickens so that the egg cell after fertilisatio can implant itself, if egg not fertilised lining breaks down again= menstruation

80
Q

menstruation

A

The process which involves the discharge of the uterine lining at the start of the menstrual cycle when an egg cell is not fertilised and it does not implant in the uterine lining. Often referred to as a period.

81
Q

what are the 4 hormones involved in the control of the menstrual cycle and pregnancy

A

fsh, lh, progesterone, oestrogen

82
Q

where is progesterone and oestrogen produced

A

both in the ovary, however progesterone by corpus luteum in the ovary

83
Q

where is lh and fsh produced

A

in the pituitary gland

84
Q

describe the menstrual cycle in terms of hormone action

A

1.level of progesterone low inhibit releason of FSH
2.levels of FSH rise, causes an egg to mature, stimulates releasion of oestrogen (re builds uterus lining)
3.levels of oestrogen rise, inhibts releasion of FSH, preventing more than one egg maturing at a time
4.oestrogen stimulates releasion of LH which stimulates the releasing of the maturest egg from its follicle into oviduct
5.empty follicle, becomes corpus lutheum, releases progesterone, inhibits releasion of FSH and LH
6.progesterone thickens the uterus lining, if women does not become fertilised, levels of progesterone fall, inhibiting menstruation to occur

85
Q

what happens if women becomes pregnant in terms of hormones

A

corpous luteum continues to release oestrogen and progesterone
which later placenta controls production of these hormones
ensuring that:
-no more eggs are released from the ovaries
-maintain a thick uterine lining to support the growing fetus
-prevent the muscles of the uterus contracting, which would cause the early delivery of a premature baby.

86
Q

sti

A

sexually transmitted infection, An infection that is transmitted via body fluids through sexual contact. can be caused by both virsues or bacterias

87
Q

how is the spread of STI’s controlled

A

avoid sexual contact or use protection
limiting number of sexual partners
being tested for an sti

88
Q

what is HIV

A

a pathogen that causes an sti
human immunodeficiency virus
can lead to aids
only transmitted through direct contact with certain bodily fluids eg, blood, semen, vaginal fluid which can get into blood by, unprotected sex, cuts, sores, contaminated needles, can be transmitted from mother to chid during birth or breast-feeding

biology igcse (25 decks)

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