16. Reproduction Flashcards
1
Q
Describe asexual reproduction
A
a process resulting in the production of genetically
identical offspring from one parent
2
Q
Describe 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
3
Q
Define fertilisation
A
the fusion of the nuclei of gametes
4
Q
Are nuclei of gametes haploid or diploid?
A
haploid
5
Q
Is the nucleus of a zygote haploid or diploid?
A
diploid
6
Q
Function of the petal
A
attracts insects, birds or mammals to carry out pollination
7
Q
Function of the sepals
A
protects the growing flower and helps it to stop it drying out
8
Q
Function of the stamen
A
produces male gametes (pollen) and provides correct structures and conditions necessary for pollen transfer
9
Q
Function of the filament
A
holds the anther in a position where it is able to transfer its pollen to an insect/mammal/bird
10
Q
Function of the anther
A
produces pollen grains (contain plant’s male gametes)
11
Q
Function of the carpel
A
produces female gametes + provides structures/conditions necessary for fertilisation
12
Q
Function of the style
A
supports and presents stigma in position where it can receive pollen (from insect/bird/mammal)
13
Q
Function of the stigma
A
traps pollen from other flowers
14
Q
Function of the ovary
A
contains ovules (which contain female gametes) which develop into seeds after fertilisation
15
Q
Function of the ovules
A
produces and contains female gametes, which upon fertilisation develop into seeds
16
Q
Advantage of self pollination:
A
plants do not rely only on pollinators
17
Q
Disadvantages of self pollination:
A
- reduces genetic variation within a population of plants
- reduces ability to of a population to respond to changes in environment (such as changes in climate or introduced diseases)
18
Q
Advantages of cross pollination:
A
- genetic variation increases within a population of plants
- improves the ability of the population to respond to changes in the environment and to disease
19
Q
Disadvantage of cross pollination:
A
- relies solely on insects (pollinators)
20
Q
What are the advantages of asexual reproduction?
A
- only one parent needed
- no time and energy spent on finding mate
- reproduction occurs quickly
- less time and energy needed
- no genetic variation: crop farming
21
Q
What are the disadvantages of asexual reproduction?
A
- no genetic variation - more susceptible to pathogens + vulnerable to environment changes
22
Q
What are the advantages of sexual reproduction?
A
- genetic variation
- more resistant to environment
- farmers can perform selective breeding
23
Q
What are the disadvantages of sexual reproduction?
A
- time and energy to find mate
- time and energy
- slower
- involves two parents
24
Q
How many number of flowers/plants do wind pollinated and insect pollinated have?
A
wind pollinated: many small
insect pollinated: fewer, larger
25
What is the plant population growth pattern
in wind pollinated and insect pollinated flowers?
wind pollinated: dense population
insect pollinated: small groups
26
How are the petals in wind and insect pollinated flowers?
wind pollinated: dull and small
insect pollinated: bright large
27
What are two adaptations of an insect pollinated flower that a wind pollinated flower doesn't have?
good scent and nectar
28
How are the pollen grains in wind pollinated flowers?
smooth, small, light, not many
29
How are the pollen grains in insect pollinated flowers?
sticky, large, heavy, many
30
How are the stamens in wind pollinated flowers?
pendulous, long filaments, exposed anthers
31
How are the stamens in insect pollinated flowers?
short filaments with enclosed anthers
32
How are the carpels/ovary in wind pollinated flowers?
exposed
33
How are the carpels/ovary in insect pollinated flowers?
enclosed
34
How is the stigma's surface in wind pollinated flowers?
sticky, feathery, exposed
35
How is the stigma's surface in insect pollinated flowers?
sticky, flat, enclosed
36
Describe pollination
the transfer of pollen
grains from an anther to a stigma
37
Describe self-pollination
the 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
38
What is cross pollination?
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
39
What are the effects of SELF-POLLINATION on a population in terms of variety, capacity to respond to changes in environment + reliance on pollinators?
- fewer genetic variation
- lower capacity to respond to changes in environment
- relies less on pollinators
40
What are the effects of CROSS-POLLINATION on a population in terms of variety, capacity to respond to changes in environment + reliance on pollinators?
- more genetic variation
- higher capacity to respond to changes in environment
- relies a lot on pollinators
41
When does fertilisation occur in plants?
when a pollen nucleus fuses with a nucleus in an ovule
42
What are three factors needed for germination of seeds?
water, oxygen and a suitable temperature
43
What enzymes are used in germination and how?
amylase breaks down starch into glucose, which is to be used by the embryo to grow
44
Describe the growth of the pollen tube and its entry into the ovule.
1. pollen lands on stigma and are recognised by the receptors on stigma surface
2. pollen tube grows down the style towards ovary
3. pollen tube penetrates wall of the ovary to reach the ovule
4. two male gametes, the sperm, inside the pollen grain move down pollen tube, reaching the ovule.
5. The nucleus of one of the two sperm fuses with the egg cell to form a zygote (fertilisation)
6. the petals, stamen and sepals wither and fall from flower
7. ovary grows and matures into fresh fruit: fertilised ovule turns into seed of the fruit
45
Function of the testes
production of sperm cells (by meiosis) and testosterone
46
What is testosterone?
male hormone involved in primary: sperm production- and secondary: penis enlargement, deep voice, body hair, shoulder enlargement, "aggressiveness" (sexual male characteristics)
47
What is the function of the scrotum?
sac enclosing testes outside of the body - protection and to ensure a proper temperature in testicles (35-33 deg.C)
48
What is the function of the sperm duct:
sperm passes to urethra
49
What is the function of the prostate gland?
lubricating secretion for semen: releases fluid rich in sucrose (which sperm cells will use as a source of energy in aerobic respiration)
50
What is the function of the urethra?
releases urine from urinary bladder for excretion and during ejaculation releases semen
51
What is the function of the penis?
erectile tissue and spongey muscle that fills with blood when men is sexually aroused: penis becomes erect and can be inserted inside the vagina
52
What is the function of the ovaries?
production of egg/follicle cells by meiosis and oestrogen + progesterone
53
What is oestrogen?
female hormone involved in primary - follicle production - and secondary - breast development, hips enlargement, body hair and fat deposits develop (sexual female characteristics)
54
What is the function of the oviducts?
* tube that moves follicle cells from the ovary towards the uterus using peristalsis and ciliated cells
* usual site for fertilisation
55
What is the function of the uterus?
muscular organ where embryo implants, foetus grows and further contracts during birth/labour so baby is delivered
56
What is and what is the function of the cervix?
muscular opening for uterus
- dilates for birth,
- acts as a barrier against sperm cells,
- opens when a woman is ovulating so it increases chance of fertilisation
57
What is and what is the function of the vagina?
muscular tube where:
- blood is released out of the body during menstruation,
- semen is deposited during sexual intercourse,
- passageway of natural child birth
58
Describe fertilisation in humans
fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell)
59
How are sperm adapted to their function?
flagellum: important for movement
mitochondria: important for aerobic respiration to keep flagellum moving
enzymes in acrosome: break down jelly coat present in the egg
60
How is an egg cell adapted to its function?
- jelly coat: changes stiffness when sperm cell penetrates, avoiding penetration of other sperm cells, avoiding polyspermy
- energy stores in cytoplasm: allows egg to survive for several days + nourishes zygote if fertilisation occurs until it can implant in the wall of the uterus
61
Compare male and female gametes in terms of: size, mobility and numbers
Female: large cell size, doesn't move (is moved), one per menstrual cycle
Male: small cell size, moves using flagellum, millions per ejaculation (live for up to 5 days)
62
What happens to the zygote in early development?
the zygote forms an embryo which is a ball of cells that implants into the lining of the uterus
63
State the functions of the umbilical cord.
- connects the foetus to the placenta
- contains blood vessels which transport nutrients, oxygen and waste products
64
State the functions of the placenta.
- respiration
- excretion
- nutrition
- immunity
- hormonal
65
What is the placenta?
a very thin membrane allowing diffusion to take place between maternal and baby blood ( there is very close contact between maternal and baby blood, but they don't mix to avoid coagulation of different blood types)
66
Placenta: respiration
allows diffusion of oxygen from mother to foetus and CO2 from foetus to mother
67
Placenta: excretion
allows diffusion of waste products produced by the baby such as lactic acid, urea, and bicarbonates into mother's blood
68
Placenta: nutrition
allows diffusion of glucose, vitamins, and minerals from mother to foetus
69
Placenta: immunity
mother's antibodies pass to baby
70
Placenta: hormonal
placenta releases 3 hormones to maintain pregnancy (HCG, oestrogen and progesterone)
71
What is the intervillous space?
part of the placenta that surround the villi and contains maternal blood, has low pressure so exchange of materials is constantly done
72
Describe the thickening (luteal) phase
corpus luteum releases progesterone causing endometrium to thicken for implantation
73
Describe the menstruation phase
endometrium sheds, FSH is released, stimulating growth and maturation of 1 egg
74
Describe the follicular phase
follicles grow and mature, oestrogen releases as response to FSH stimulus (positive feedback) causing endometrium to rebuild
75
Describe the ovulation phase
oestrogen stimulates release of LH from pituitary gland, causing release of egg into oviduct: empty follicle, without egg, is called corpus luteum
76
Where are oestrogen and progesterone released from and what do they target?
released by ovary, targets the uterus lining
77
What is the role of FSH?
stimulates growth and development of a mature egg in the ovary
78
What is the role of LH?
stimulates ovulation and development of the corpus luteum
79
What is the role of oestrogen?
builds up endometrium after menstruation
80
What is the role of progesterone?
thickens endometrium after ovulation
81
What happens to the corpus luteum if the egg IS NOT fertilised?
corpus luteum is degenerated therefore levels of progesterone fall, leading to menstruation
82
What happens to the corpus luteum if the egg IS fertilised?
blastocysts releases a hormone that stimulates maintenance of corpus luteum: therefore levels of progesterone are kept high during all pregnancy so endometrium doesn't shed
83
What is an STI (sexually transmitted infection)?
an infection that is transmitted through sexual contact
84
What is HIV?
human immunodeficiency virus- a pathogen that causes an STI
85
What may HIV infection lead to?
AIDS
86
Describe the methods of transmission of HIV
- direct contact with certain body fluids from an infected person: eg blood, semen, vaginal fluid
- can happen through: - unprotected sex,
- cuts and sores,
- using contaminated needles for injecting drugs,
- receiving blood transfusions,
- mother to child during childbirth/pregnancy/breast-feeding
87
How is the spread of STIs controlled?
using condoms
88
What is the amniotic sac?
thin sac that protects the developing fetus within the uterus
89
What is amniotic fluid?
fluid that surrounds + protects the developing fetus within the amniotic sac
90
True or false: No toxins or pathogens can pass across the placenta.
F- some pathogens and toxins can pass across the placenta and affect the fetus
