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chapter 16 Flashcards

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1
Q

describe asexual reproduction

A

the process that produces genetically identical offspring from 1 parent

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2
Q

Describe some properties of asexual reproduction

A
  1. does not involve gametes or fertilisation
  2. only 1 parent required , so no variation and no mixing of genetic info
  3. offspring is genetically identical
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3
Q

identify examples of asexual reproduction

A
  • plants
  • bacteria via binary fission
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4
Q

identify advantages of asexual reproduction

A

only 1 parent needed
no gametes needed
no fertilisation needed
less energy needed
good characteristics passed onto offspring
population can be increased rapidly with right conditions
time and energy efficient
faster than sexual reproduction

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5
Q

identify disadvantages of asexual reproduction

A

less or no adaptations to changing evironment
increase risk of extinction
less or no resistance to disease
natural selection cannot occur

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6
Q

describe sexual reproduction

A

a process involving the fusion of the nuclei of 2 gametes to form a zygote and the production of offspring that are genetically different from each others

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7
Q

describe fertilisation

A

the fusion of the nuclei of gametes

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8
Q

describe the difference of gametes and zygote

A

Gametes
- sex cell
- contain half the number of chromosomes 23
- haploid nuclei

Zygote
male and female gametes fuse together
diploid nucleus ( 46 chromosomes )

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9
Q

describe the advantages of sexual reproduction

A

has variation
has adaptation to changing environment
lower risk of extinction
has resistance to some disease
natural selection can occcur

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10
Q

describe the disadvantages of sexual reproduction

A

2 parents required
gametes and fertilisation needed
more energy
difficult for isolated members to reproduce

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11
Q

state the structure of flowering plants and the functions

A

Sepal - protect flower bud
Petals - colourful, attract insects
Anther - produce pollen ( male gametes ), meiosis occur
Filaments - supports anther
Stigma - receive pollen
Style - connect stigma to ovary
Ovary - contains ovule
Ovule - contain female gametes , for fertilisation

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12
Q

Describe the differences between insect and wind pollinated flowers

A

Insect - pollinated :
Petals - bright & colourful
Scent & Nectar - present
Number of pollen - small amounts
Feature of pollen - sticky and spicky, larger , heavier
Anther - inside flower, to allow insect to brush against them while taking nectar
Stigma - inside the flower , to receive pollen easily as insect brush against them

Wind-pollinated :
Petals - dull and small
Scent & Nectar - not present
Number of pollen - large quantities
Feature of pollen - light and small, smooth
Anther - hangs outside, to release pollen easily as wind blows
Stigma - Hard outside , feathery to increase surface area to catch pollen

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13
Q

Describe pollination

A

the transfer of pollen grains from an anther to a stigma

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14
Q

Describe self pollination

A

The transfer of pollen grains from anther to stigma within the same plants

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15
Q

Describe cross pollination

A

The transfer of pollen from anther to stigma of different plants but same species

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16
Q

Describe the advantages of self pollination

A

no pollinators needed
less / no wastage of pollen
higher chance of pollination and fertilisation

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17
Q

Describe the disadvantages of self pollination

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A

less/no variation
less/no adaptation to changing environment
less/no resistance to disease

18
Q

Describe the advantages of cross pollination

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A

more variation
more adaptation to changing environment
more resistance to diseases
natural selection can occur

19
Q

Describe the disadvantages of cross pollination

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A

require pollinators
more wastage of pollen
lesser chances of pollination and fertilisation

20
Q

Describe the growth of pollen tube and fertilisation

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A

Pollen grain landed on the stigma , germinates and form pollen tube
Pollen tube grows down the style . The male nuclei inside the pollen tube moves down the tube ass the tube grows down the style towards the ovary.
The male nuclei then enters the ovule via micropyle and fuses with the female nuclei to form zygote . Zygote starts to divide and become embryo . Ovule becomes the seed and ovary becomes the fruit

21
Q

State the parts and function of the male reproductive system

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A

Testes - produce male gametes ( sperm ) and hormones ( testosterone )
Epididymis - store mature sperms
Scrotum - a sac that keeps the testes outside the body to ensure sperms are kept at a lower body temperature
Sperm ducts - link testis to urethra
Prostate glands - produce fluid ( semen that provides nutrients to sperm cell )
Urethra - pass semen and urine through penis
Penis - becomes firm during sexual intercourse , passes urine out of body

22
Q

State the parts and function of the female reproductive system

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A

Ovaries- contains egg cell , secrete oestrogen and progesterone
Oviducts - carries ovum to uterus , site of fertilisation, lined with epithelial cells to push the ovum to uterus
Uterus - contains uterus lining where zygote will be implanted to develop into a foetus
Cervix- a ring of muscles at lower end of the uterus that separates the vagina from the uterus
Vagina- where penis will enter during intercourse and sperm are deposited

23
Q

Define fertilisation

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A

The fusion of the nuclei of from a male gamete and a female gamete

24
Q

Describe the features of the sperm including the size, movement and its adaptive features

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A
  1. contains acrosome ( contains enzyme to digest the jelly layer of egg cells during fertilisation )
  2. Contain mitochondria ( to provide energy for the tail of the sperm to swim )
  3. Has tail called flagellum ( allows sperm to swim towards egg cell )

Size : SMALL
Movement: MOVABLE
Number produced : MILLIONS/DAY
Site of production: TESTES

25
Describe the features of the egg cell including the size, movement and its adaptive features
Jelly coating that changes after fertilisation ( forms impenetrable barrier to prevent entry of other sperms ) Cytoplasm stores energy ( stores energy to allow zygote to divide by mitosis into embryo ) Size : LARGE Movement: CANNOT MOVE Number produced : ONE/MONTH Site of production: OVARY
26
State the process after fertilisation
After fertilisation, zygote travels to uterus. Takes around 3 days, during which zygote will divide several times by mitosis to form a ball cells called embryo Embryo in uterus will embed itself in uterus lining. Process called implantation
27
How long is the gestation period
9 months first 12 weeks major development of organs
28
State the function of the amniotic sac and fluid
Amniotic fluid: 1. cushion fetus from shock 2. protects fetus from physical injury 3. allows fetus to move for bone and muscle development 4. acts as lubricant 5. maintains constant temperature Amniotic sac: 1. contains amniotic fluid 2. prevent entry of pathogens
29
state the functions of the umbilical cord
joins the fetus's blood to the placenta for exchange of substances and removal of waste products Umbilical vein : transports oxygen, nutrients, antibodies, hormones ( placenta to foetus ) Umbilical artery : transports carbon dioxide , urea, water ( foetus to placenta )
30
Describe the placenta and its functions
1. allows exchange of substances 2. Prevents entry of pathogen 3. prevent mixing of blood 4. secrete progesterone which is used to maintain thickness of uterus lining
31
How is the placenta adapted for diffusion of the substances
1. large surface area ( contain villi to increase surface area , which speeds up diffusion ) 2. thin walls ( shorter diffusion distance ) 3. Network of blood vessels ( allow transport of substances to occur faster )
32
State the entry of chemicals that can cross the placenta into the foetus's blood
HIV virus, Rubella virus, alcohol, nicotine
33
State teh secondary characteristics for male and female during puberty
male: 1. development of facial features 2. development of more muscles 3. deeper voice 4. wider shoulders female: 1. development of hair 2. breast growth 3. wider hips 4. menstruation
34
Describe the menstrual cycle in terms of before period and after period
B4: egg is released once a month. b4 the egg is released, the lining of the uterus becomes thicker and spongy to prepare for implantation During: after the egg dies, uterus lining break down and discharges through vagina KNown as menstruation
35
Describe the hormones involved in the menstrual cycle and their functions and sites of secretion
Follicle stimulating hormone ( FSH ) Site of secretion: Pituitary gland Functions: 1. stimulate the growth of follicle in the ovary 2. allow maturation of egg cells 3. follicle stimulates release of oestrogen Oestrogen Site of secretion : ovary Functions : 1. promotes growth and repair of the endometrium wall / uterus lining 2. for implantation and pregnancy 3. oestrogen stimulates release of LH Luteinising hormone ( LH ) Site of secretion : pituitary gland Functions : 1. causes ovulation to occur 2. the release of egg cells into oviduct 3. stimulates the ovary to produce progesterone Progesterone Site of secretion : ovary , secreted by yellow body Functions: 1. thicken the wall of uterus enriched with blood vessels for pregnancy 2. maintain thickness of the uterus lining 3. prevents secretion of FSH and LH
36
Describe the order of the hormones in terms of the days of the menstrual cycle
day 1-7 - period ( break down of uterus lining ) - FSH released day 8-13 - follicles stimulate release of oestrogen - oestrogen repair and allow growth of uterus lining day 14 - LH secreted, causing ovulation day 15-28 - progesterone secreted - maintains thickness of lining
37
Describe what happens if the egg is not fertilised
NO fertilisation, corpus Luteum degenerates NO more progesterone secreted Back to Day 1
37
Describe what happens if the egg is fertilised
Corpus Luteum does not degenerate so quickly Progesterone continues to be secreted until embryo implanted and a placenta develops Placenta secrete progesterone throughout pregnancy to maintain thickness of uterus lining
38
Describe sexually transmitted disease
An infection that is transmitted through sexual contact
39
Describe methods of transmission of HIV
1. through shared needles 2. blood transfusion with infected blood 3. mother to fetus via placenta 4. mother to baby via breastfeeding
40
Explain how the spread of STI in controlled
1. limit number of sexual partners 2. not having unprotected sex 3. getting tested 4. raising awareness by educational programmes

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