Download 22.4 Sexual reproduction in flowering plants

22 Reproduction
•
22.1 What is reproduction?
•
22.2 Asexual reproduction in bacteria (Extension)
•
22.3 Asexual reproduction in flowering plants
(Extension)
•
22.4 Sexual reproduction in flowering plants
(Extension)
•
22.5 Fruits and seeds (Extension)
22 Reproduction
•
22.6 The advantages and disadvantages of
sexual reproduction compared with asexual
reproduction in flowering plants (Extension)
•
22.7 Sexual reproduction in humans
•
22.8 Human embryos
•
22.9 The birth process
•
22.10 Parental care
•
22.11 Birth control
•
Mind Map
22.1 What is reproduction?
What is
22.1 What is reproduction?
a process that living organisms
can produce new offspring
to replace those members
that die
22.1 What is reproduction?
Reproduction
Asexual
reproduction
Sexual
reproduction
22.1 What is reproduction?
is the production
of offspring
from a single
parent
without the
fusion of gametes
22.1 What is reproduction?
is the production
of offspring
from the
fusion of gametes
22.1 What is reproduction?
Asexual
Reproduction
Sexual
Reproduction
Number of parents
involved
One
Two
Involvement of
gametes
No
Yes
Cell division involved
Mitosis
Meiosis
Does fertilisation
occur?
No
Yes
Genetic make-up of
the offspring
Identical to
parent
Different from
parents
22.2 Asexual reproduction in bacteria
in bacteria
22.2 Asexual reproduction in bacteria
Bacteria undergo
binary fission
to form
two identical
daughter cells
22.3 Asexual reproduction in flowering plants
in flowering plants
22.3 Asexual reproduction in flowering plants
1
2
3
4
5
22.3 Asexual reproduction in flowering plants
Bud
germinates
Vegetative
propagating
organ
Bud
Storage organ
provides food
for the growth
of new shoots
Adventitious roots are
formed to absorb water
1
2
22.3 Asexual reproduction in flowering plants
Green leaves
develop
Vegetative
propagating
organ
Bud
Carry out
photosynthesis
Storage organ dries up
as food is being used up
1
2
3
22.3 Asexual reproduction in flowering plants
Photosynthetic product
is stored in
a new storage organ
Vegetative
propagating
organ
Bud
A new
storage organ
1
2
3
4
22.3 Asexual reproduction in flowering plants
the storage organ
remains dormant
until next year
A bud is formed for
next growing season
Vegetative
propagating
organ
Bud
1
2
3
4
5
22.3 Asexual reproduction in flowering plants
Many flowering plants
can reproduce asexually
by this method
Vegetative
propagating
organ
Bud
 vegetative propagation
22.3 Asexual reproduction in flowering plants
bulbs
Also called
perennating
organs
Vegetative
propagating
organ
Bud
corms
rhizomes
tubers
22.3 Asexual reproduction in flowering plants
Bulbs
Stores food
fleshy leaf
An onion bulb
bud
Provides food for the
germination of bud
22.3 Asexual reproduction in flowering plants
Corms
Provides food for
the germination
of bud
bud
corm
Stores food
A Gladiolus corm
22.3 Asexual reproduction in flowering plants
Rhizomes
bud
rhizome
Stores food
Provides food for the
germination of bud
A lotus rhizome
22.3 Asexual reproduction in flowering plants
Tubers
bud
tuber
Stores food
Potato tubers
Provides food for
the germination
of bud
22.3 Asexual reproduction in flowering plants
Perennating
organ
Origin of
organ
Region of
food storage
Examples
Bulb
Stem
Fleshy scale
leaves
Onion,
daffodil
Corm
Stem
Swollen stem
base
Gladiolus,
Crocus
Rhizome
Stem
Entire length of
horizontal stem
Ginger,
lotus, iris
Stem
Tip of side
branch of stem
Potato,
arrowhead
Tuber
22.3 Asexual reproduction in flowering plants
Experiment 22.1
To cultivate any vegetative propagating organ of flowering
plants
1. Choose a vegetative propagating organ of flowering plants,
such as tuber, bulb, rhizome or corm.
2. Put the vegetative propagating organ on a pot of soil
(sandy soil is more suitable) and cover it with soil of
2 cm thickness.
3. Water it once or twice a day.
4. Observe its change during growth.
22.3 Asexual reproduction in flowering plants
Experiment 22.2
To examine one vegetative propagating organ
1. Choose one vegetative propagating organ which is
beginning to sprout into a new plant.
2. Observe it carefully and identify the parts in
vegetative propagation.
22.3 Asexual reproduction in flowering plants
Advantages of
vegetative propagation
1
As large food reserves
are provided for daughter plants
It is a rapid way of reproduction
22.3 Asexual reproduction in flowering plants
Advantages of
vegetative propagation
2
Offspring are
genetically identical to parent
Desirable characters
can be retained
22.3 Asexual reproduction in flowering plants
Advantages of
vegetative propagation
3
No external agents
are required
It is a surer way
of reproduction
22.3 Asexual reproduction in flowering plants
Disadvantages of
vegetative propagation
1
Overcrowding may occur
It leads to competition for the
same resources among the
offspring
22.3 Asexual reproduction in flowering plants
Disadvantages of
vegetative propagation
2
No genetic variation occurs in offspring
This decreases the ability of offspring to adapt
to changes in the surroundings
22.3 Asexual reproduction in flowering plants
Disadvantages of
vegetative propagation
3
The parent plant and the daughter plants
are linked together
Diseases of the parent plant are
rapidly transmitted to the offspring
22.3 Asexual reproduction in flowering plants
Advantages
Disadvantages
Rapid way of
reproduction
Competition among
offspring
Desirable characters
can be retained
Less ability to adapt
to changes
Surer way of
reproduction
Disease transmission
22.4 Sexual reproduction in flowering plants
in flowering plants
22.4 Sexual reproduction in flowering plants
The sex organ in flowering plant is
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
3
a
a
b
b
c
d
2
1
5
4
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
2. The sepals of most
flowers are green for
photosynthesis
1. Protects
the flower
buds
sepal
1
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
1. Brightly
coloured to
attract insects
2
petal
2. Has insect-guides which
guide insects to the base
of the petals to get nectar
from nectary
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
Secretes nectar for
insects to feed on
nectary
5
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
stamen
3
a
anther
filament
b
Produces
pollen grains
Supports anther
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
3
a
a
b
b
c
d
2
1
5
4
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
a
stigma
style
b
carpel
4
c
ovary
ovule
d
22.4 Sexual reproduction in flowering plants
Structure and functions of a flower
Receives
pollen grains
stigma
Allows pollen
tube to grow
through
style
carpel
ovary
ovule
Contains
ova
Contains
ovules
22.4 Sexual reproduction in flowering plants
Experiment 22.3
Examination of flowers
1. Obtain a flower, such as Bauhinia, Gladiolus, Lily or
Cassia.
2. Identify the floral parts. How many sepals, petals, stamens
and carpels are there? Use a table to record these floral parts.
3. Use a scalpel to cut open the carpel longitudinally.
Can you see any ovules? You can use a hand lens to make
your observation.
4. State the functions of the floral parts.
22.4 Sexual reproduction in flowering plants
Pollination
pollen grain
22.4 Sexual reproduction in flowering plants
Pollination
22.4 Sexual reproduction in flowering plants
Pollination
is the transfer of
pollen grains
from the anther
to the stigma
22.4 Sexual reproduction in flowering plants
Pollination
produces
pollen sac
anther
pollen
grains
carry male
gametes
when anther is mature
it splits
open
22.4 Sexual reproduction in flowering plants
Pollination
ovary
22.4 Sexual reproduction in flowering plants
Pollination
ovule
contains
ovum
22.4 Sexual reproduction in flowering plants
Pollination
Insect
pollination
Wind
pollination
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Larger
Size
Wind-pollinated
flower
Smaller
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Petal
Colour
Brightly-coloured
Wind-pollinated
flower
Dull-coloured
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Present
Scent
Wind-pollinated
flower
Absent
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Present
Nectary
Wind-pollinated
flower
Absent
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Anther
Enclosed within flower,
to brush pollen grains
onto insect body
Wind-pollinated
flower
Hanging out of flower,
for catching the wind
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Stigma
Enclosed within flower,
to brush the insect body
to get pollen grains on it
Wind-pollinated
flower
Large and feathery,
exposed, for catching
pollen
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Pollen
grains
Produced in small number
Wind-pollinated
flower
Produced in large number
Lighter,
with
smooth
surfaces
Rougher, heavier
with spikes
for sticking to insects
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flower
Occurrence
Appear in warmer
seasons, when there are
more active insects
Wind-pollinated
flower
In windy
area
Sometimes
appear in
colder and
drier
seasons
22.4 Sexual reproduction in flowering plants
Insect-pollinated
flowers
Wind-pollinated
flower
Size
Large
Small
Petals
Brightly coloured
Dull coloured
Nectary
Present &
produces nectar
Absent
Scent
Strongly scented
No scent
Inside the flower
Hanging out
of the flower
Anthers
22.4 Sexual reproduction in flowering plants
Stigma
Insect-pollinated
flowers
Wind-pollinated
flower
Inside the flower
Large, feathery,
exposed
Rougher, heavier
with spikes
Lighter with smooth
surfaces
Produced in small
numbers
Produced in large
numbers
In warmer seasons
In colder & drier
seasons
Pollen grains
Occurrence
22.4 Sexual reproduction in flowering plants
Experiment 22.4
To examine the adaptive features of insect-pollinated and windpollinated flowers
1. Your teacher will give you some insect-pollinated flowers
and some wind-pollinated flowers.
Which is which? How do you know?
2. With the aid of a hand lens, examine each flower carefully.
Which features does it have?
22.4 Sexual reproduction in flowering plants
Pollination
Selfpollination
Crosspollination
22.4 Sexual reproduction in flowering plants
Self-pollination
Same flower
Different
flower on
the same
plant
Flower A
Flower B
22.4 Sexual reproduction in flowering plants
Self-pollination
Transfer of pollen from the
anther to the stigma of the
1. SAME flower, or
2. another flower on
the SAME plant
22.4 Sexual reproduction in flowering plants
Same species
Plant A
Flower A
Cross-pollination
Plant B
Flower B
22.4 Sexual reproduction in flowering plants
Cross-pollination
Transfer of pollen
to a flower of
DIFFERENT plant
of the SAME species
22.4 Sexual reproduction in flowering plants
Fertilisation
Male gamete fuses with
the egg cell (ovum)
to form a zygote
22.4 Sexual reproduction in flowering plants
Fertilisation
1. Stigma cells
secrete a
sugary solution
Pollen grain
sticks to
the stigma
22.4 Sexual reproduction in flowering plants
Fertilisation
Pollen tube
2. Sugary solution
stimulates the
pollen grain
to develop a
pollen tube
22.4 Sexual reproduction in flowering plants
3. Pollen tube
secretes enzyme
to digest cells
Pollen tube grows
down the style and
the ovary
Fertilisation
Pollen tube
22.4 Sexual reproduction in flowering plants
3. Pollen tube
secretes enzyme
to digest cells
Fertilisation
Male gamete
Pollen tube
Pollen tube grows
down the style and
the ovary
Carrying male
gametes towards
the micropyle of
the ovule
Micropyle
22.4 Sexual reproduction in flowering plants
3. Pollen tube
secretes enzyme
to digest cells
Fertilisation
Pollen tube
Pollen tube grows
down the style and
the ovary
Carrying male
gametes towards
the micropyle of
the ovule
Micropyle
22.4 Sexual reproduction in flowering plants
Fertilisation
4. Male gamete is
liberated into
the ovule
Pollen tube
Fuses with ovum
Fertilisation
Ovum
Micropyle
22.4 Sexual reproduction in flowering plants
Fertilisation
4. Male gamete is
liberated into
the ovule
Pollen tube
Fuses with ovum
Fertilisation
Ovum
Micropyle
22.5 Fruits and seeds
&
22.5 Fruits and seeds
Ovary
Fruit
ovary
wall
fruit
wall
ovule
seed
sepals
petals
stamens
stigma
style
wither
and fall
off
22.5 Fruits and seeds
Dispersal of seeds by fruits
is a process that seeds spread from
the parental plant
1
2
To prevent overcrowding and
reduce competition
Allows plants to colonise new areas
22.5 Fruits and seeds
Dispersal of seeds by fruits
Methods
By animals
By wind
By explosion
By water
22.5 Fruits and seeds
By animals
1
Hooks
cling to animals’ fur
3
2
Seeds are
surrounded by
hard seed coat
resist to animals’
digestive enzymes
Some are
fleshy fruits
provide food to
animals
22.5 Fruits and seeds
By wind
Hair
Wing
Light & large
surface area
allow dispersal over
a great distance
22.5 Fruits and seeds
By explosion
1 When the skin
dries out
2 The seeds are
3 The seeds are
scattered
over a wide area
suddenly
released as the
pod splits open
22.5 Fruits and seeds
By water
1
Some fruits
e.g. coconut
2
3
Contains air
space
which makes the
fruit buoyant
22.5 Fruits and seeds
Structure of dicot seeds
External
appearance
Longitudinal
section
22.5 Fruits and seeds
Structure of dicot seeds
seed coat
cotyledon
plumule
radicle
micropyle
embryo
22.5 Fruits and seeds
Structure of dicot seeds
seed coat
cotyledon
plumule
radicle
micropyle
A tough,
protective
covering
22.5 Fruits and seeds
Structure of dicot seeds
seed coat
Stores food
cotyledon
plumule
Grows into
the leafy
shoot
radicle
micropyle
Grows into
the root
22.5 Fruits and seeds
Structure of dicot seeds
seed coat
cotyledon
plumule
radicle
micropyle
Allows water
to enter
before
germination
22.6 The advantages and disadvantages of sexual reproduction
compared with asexual reproduction in flowering plants
Sexual
Asexual
22.6 The advantages and disadvantages of sexual reproduction
compared with asexual reproduction in flowering plants
Advantage
Fast – one individual
can produce a large
number of offspring
Disadvantage
All offspring are
identical, less genetic
variation
Overcrowding may
occur
Asexual
Reproduction
Only vegetative
organs are required
Diseases may be
transmitted from
parent plants to the
offspring
22.6 The advantages and disadvantages of sexual reproduction
compared with asexual reproduction in flowering plants
Sexual
Reproduction
Advantage
Disadvantage
Genetic variation
occurs, offspring have
a greater chance to
adapt to changes in
environment
Slow
More complicated –
two parents are
required
Overcrowding can be
avoided
Sex organs are
involved for mating
Diseases are not
easily transmitted to
the offspring
required fertilisation
of male and
female gametes
22.7 Sexual reproduction in humans
in humans
male female
22.7 Sexual reproduction in humans
Males
Produces sperms
& male sex
hormones
epididymis
testis
scrotum
22.7 Sexual reproduction in humans
Males
Storage of
sperms
epididymis
testis
scrotum
22.7 Sexual reproduction in humans
Males
sperm duct
transports
sperms
epididymis
testis
scrotum
22.7 Sexual reproduction in humans
Males
seminal vesicle
prostate gland
Cowper’s gland
secrete
seminal
fluid
22.7 Sexual reproduction in humans
Males
Activates &
nourishes the
sperms
Neutralises
the acidity
of vagina
seminal vesicle
prostate gland
Cowper’s gland
secrete
seminal
fluid
22.7 Sexual reproduction in humans
Males
seminal vesicles
testes
prostate glands
secrete
Cowper’s glands
secrete
seminal
fluid
sperms
semen
22.7 Sexual reproduction in humans
Males
22.7 Sexual reproduction in humans
Males
Joins the
sperm ducts to
transport sperms
urethra
penis
For copulation
22.7 Sexual reproduction in humans
in humans
male female
22.7 Sexual reproduction in humans
Females
ovary
Produces ova
and female sex
hormones
22.7 Sexual reproduction in humans
Females
oviduct
1. Possesses a ciliated
lining and a muscular wall
helps to move the ova
2. Site for
fertilisation
22.7 Sexual reproduction in humans
Females
1. Protects the
developing
embryo
uterus
2. Provides a constant
internal environment for
the embryo to develop
3. Contracts
rhythmically and
powerfully to
expel the foetus
out at birth
22.7 Sexual reproduction in humans
Females
1. Receives the
penis during
copulation
vagina
2. Acts as a
birth canal for
the foetus
22.7 Sexual reproduction in humans
Experiment 22.5
To examine the male and female reproductive systems of
dissected mammals of a human torso
1. You will be given a dissected female rat so as to show the
reproductive system. Examine it carefully. Try to identify
the ovaries, the oviducts and the uterus.
coiled
oviduct
uterus
ovary
22.7 Sexual reproduction in humans
Experiment 22.5
To examine the male and female reproductive systems of
dissected mammals of a human torso
2. You will be given a dissected male rat to show the
reproductive system. Examine it carefully. Try to identify
the penis, scrotum and sperm duct.
22.7 Sexual reproduction in humans
The structure of
22.7 Sexual reproduction in humans
Structure of sperm
For
movement
Contains
genetic materials
head
middle piece
tail
Contains
mitochondria
which supply energy
22.7 Sexual reproduction in humans
Structure of ovum
Nucleus
Contains
genetic materials
cytoplasm
Contains yolk
which nourishes
the egg and the
developing
embryo
22.7 Sexual reproduction in humans
Structure of ovum
For protection
Plasma
membrane
Jelly coat
Follicle cell
22.7 Sexual reproduction in humans
Sperm
Ovum
Size
Smaller
Larger
Shape
Tadpole-like,
with a head
and a tail
Spherical
Movement
Can swim
using a tail
Cannot move
by itself
No food reserve
Has good
reserve (yolk)
Millions produced
Much fewer
made
Food
reserve
Number
produced
22.7 Sexual reproduction in humans
22.7 Sexual reproduction in humans
Remaining part
 yellow body
A section through a human ovary
Ovum surrounded
by follicle cells
follicle
ovum
to
oviduct
Ovum is released
into the oviduct
 ovulation
Ovum is
developing
inside the
follicle
When the
ovum is
mature, the
follicle bursts
22.7 Sexual reproduction in humans
22.7 Sexual reproduction in humans
During puberty
Male
Female
Testes grow &
produce sperms
Ovaries grow &
release eggs
Secondary sexual
characteristics are
developed
Secondary sexual
characteristics are
developed
22.7 Sexual reproduction in humans
Male
Secondary sexual characteristics
1
Growth of pubic hair and
hair on face and in armpits
2
3
Deepening of voice
& enlargement of larynx
Muscle development
4
Widening of shoulders
22.7 Sexual reproduction in humans
Female
Secondary sexual characteristics
1
Growth of pubic hair
2
3
Growth and development of breasts
Widening of hips
4
More fat deposits under skin
22.7 Sexual reproduction in humans
Sex hormones
Male sex
hormone
testosterone
Female sex
hormones
oestrogen
Male
Female
secondary sexual
characteristics
secondary sexual
characteristics
22.7 Sexual reproduction in humans
22.7 Sexual reproduction in humans
Menstrual Cycle
From day 1 – day 5
Uterine lining breaks
down & passes out
with the unfertilised
ovum
Menstrual
flow
This period is called
menstruation
22.7 Sexual reproduction in humans
Menstrual Cycle
From day 5 – day 14
The uterine lining
builds up again
which is induced by
female sex hormone
22.7 Sexual reproduction in humans
Menstrual Cycle
Day 14
Ovulation occurs
22.7 Sexual reproduction in humans
Menstrual Cycle
From day 14 – day 28
The uterine lining
remains thick
and spongy
Thickened uterine lining
is ready to receive
a fertilised ovum
22.7 Sexual reproduction in humans
Menstrual Cycle
Ovary
From day 1 – day 13
After ovulation
Day 14
Follicle is
developing until
mature
Yellow body is
developed
Ovulation
22.7 Sexual reproduction in humans
Summary
Follicle starts
to develop
Follicle is
developing
until mature
Yellow
body is
developed
Thickness of
uterine lining
Menstruation
*
Uterine lining
remains thick
14
ovulation
15 - 28
Uterine
lining is
developing
1-5
6 - 13
Follicle starts to
develop again
Menstruation
starts again
Day
22.7 Sexual reproduction in humans
&
22.7 Sexual reproduction in humans
Sexual intercourse
When a male is sexually excited
Blood is pumped into the spaces
inside the penis
Penis becomes erect and hard
Erect penis is inserted into vagina of female
22.7 Sexual reproduction in humans
The sperm meets the
ovum in oviduct
The sperms swim
through uterus & into
oviduct
The semen is
squeezed into vagina
semen
Ejaculation
22.7 Sexual reproduction in humans
Fertilisation
The head of sperm
secretes enzyme
which dissolves the jelly coat
Only the head can penetrate
into & fuse with the egg
The protective membrane
becomes impenetrable to
other sperms
22.7 Sexual reproduction in humans
Fusion of gametes
Forms a
zygote
fertilised
Egg
22.7 Sexual reproduction in humans
Twins
Identical
Non-identical
22.7 Sexual reproduction in humans
Identical twins
After fertilisation,
ONE zygote is formed
It divides into two cells by mitosis
Each cell develops separately
into a normal embryo
Twins are of the same sex &
are genetically identical
22.7 Sexual reproduction in humans
Non-identical twins
Two eggs are shed from the
ovary & fertilised
TWO zygotes are formed
Twins may have different sexes;
They are genetically different
22.8 Human embryos
22.8 Human embryos
4. An embryo
is formed
3. Zygote divides
successively by
mitosis
2. Fertilisation
occurs in
oviduct and a
zygote is formed
5. Embryo embedded
in the uterine lining
 implantation
1. An
ovum is
released
22.8 Human embryos
Development of embryo
3placenta
umbilical
cord
2
uterine lining
6
1 embryo
amniotic
fluid
4
5 amnion
cervix7
vagina
8
22.8 Human embryos
umbilical cord
Carries CO2 &
wastes towards
the placenta
umbilical artery
embryo
22.8 Human embryos
Carries O2 ,
food &
antibodies to
the foetus
umbilical vein
umbilical artery
embryo
22.8 Human embryos
CO2 & wastes diffuse
from foetal blood
into maternal blood
O2 ,nutrients &
antibodies diffuse
from maternal blood
into foetal blood
maternal blood
capillary of foetus
22.8 Human embryos
Placenta
Place
for material
For nutrition,
exchange
breathing and
excretion
of the
between
foetus
foetus
& mother
22.8 Human embryos
Adaptations of placenta
1
Placenta possesses many
finger-like projections
called villi
To increase the surface
area for exchange of
materials by diffusion
22.8 Human embryos
2
Thin membrane
between maternal
and foetal blood
To decrease the
distance for faster
diffusion of materials
across it
22.8 Human embryos
3
Maternal and foetal
blood are separated
To prevent the entry of
germs from maternal
blood to foetus blood
22.8 Human embryos
3
Maternal and foetal
blood are separated
To prevent the high
pressure in maternal
blood from damaging
the delicate blood
vessels of the foetus
22.8 Human embryos
3
Maternal and foetal
blood are separated
To prevent mixing of
blood if the blood
groups of mother and
foetus are incompatible
22.8 Human embryos
The foetus requires
about 40 weeks
(about 280 days) of
development
gestation period
22.9 The birth process
The
22.9 The birth process
1
Uterus muscles
contract rhythmically
and powerfully
2
Cervix dilates
22.9 The birth process
3
Amnion breaks
Amniotic fluid flows
out through the vagina
Lubricates the
passage for foetus to
come out
22.9 The birth process
4
Continuous
contraction of
uterus muscles
Push the foetus out
through the vagina
22.9 The birth process
Once the baby has
come out
its umbilical cord is
clamped & then cut
The scar becomes
the navel
22.9 The birth process
After birth,
placenta becomes detached from
the wall of the uterus a few hours
after the birth of baby
& passes out
through the vagina
This is called afterbirth
22.10 Parental care
22.10 Parental care
The parents not only provide the babies
with food, clothes & shelter
but also teach the young children how to
look after themselves
This increases the chance of survival of
the young before they become mature
22.10 Parental care
After birth, the baby has a
natural instinct to suck
It stimulates the breasts
of the mother to release milk
This process is called
lactation
22.10 Parental care
The advantages of breast-feeding
1
Human milk is uniquely suited
for human babies
Human milk is easy to
digest & contains most of
the essential nutrients
It contains antibodies
which help the baby to resist infection


22.10 Parental care
The advantages of breast-feeding
2
Breast-fed babies are healthier
Antibodies in human milk
help to reduce the
incidence of bacterial
infections
Breast-fed babies are less likely
to have diarrhoea
22.10 Parental care
The advantages of breast-feeding
3
Breast-feeding keeps
women healthier
Breast-feeding helps
mothers recover from
childbirth
It is believed to reduce the risk of breast
and ovarian cancers
22.11 Birth control
22.11 Birth control
Human population
is growing rapidly
Run out of
resources,
pollution,
overcrowding, ……
Contraceptio
n helps to
reduce the
growth of
human
population
22.11 Birth control
Body temperature (℃)
A
B
C
Menstruation
Why?
A C
Which
period(s) is/are safe
Day of the menstrual cycle
for intercourse without fertilisation?
22.11 Birth control
Body
(℃)
1 temperature
Ovulation
Natural (rhythm)
method
A
B
C
Menstruation
NOT
RELIABLE!!!
A C
It is because
ovulation is most likely to
Day of the menstrual cycle
take place in period B
22.11 Birth control
2
Contraceptive pills
Synthetic hormones
prevent ovulation
Many
side effects
water retention,
high blood pressure,
getting fatter,
cardiovascular
diseases, headaches
22.11 Birth control
3
Barrier method
A device that prevents the sperms & egg
from coming into contract with each other
Female
Male
Diaphragm
Condom
Female
condom
22.11 Birth control
3
Barrier method
uterus
Diaphragm
(a dome-shaped rubber)
fits over the
entrance of the uterus
22.11 Birth control
4
Surgical method
(or sterilisation)
Male
Female
Vasectomy
Tubal ligation
Do not affect
the formation of gametes
and sex hormones
22.11 Birth control
4
Surgical method
Sperm ducts
are cut & tied
The semen contains
no sperm
Vasectomy
22.11 Birth control
4
Surgical method
Tubal ligation
Sperm cannot reach
the egg
Tubal ligation
22.11 Birth control
5
Intrauterine devices (IUD)
A small plastic or
copper device is put
into the uterus
Prevent fertilised egg
from implanting in the
uterine wall
22.11 Birth control
Summary
1
Natural (rhythm)
method
2
Contraceptive
pills
3
Barrier method
4
Surgical method
5
Intrauterine devices
(IUD)
Mind Map
Reproduction
two types
asexual reproduction
in bacteria
binary fission
sexual reproduction
in flowering plants
vegetative
propagation
examples of
perennating organs
1. bulb
2. corm
3. rhizome
4. tuber
Mind Map
sexual reproduction
in flowering plants
in humans
pollination
sexual intercourse
fusion of
fusion of
male gamete
(inside pollen
grain)
male gamete
(sperm)
and
and
female gamete
(ovum)
female gamete
(ovum)
this process is called
fertilisation
fertilisation
not occurs
menstruation
Mind Map
fertilisation
produces
produces a
fruit
zygote
prevention of
this process
in human
birth control
contains
seeds
implantation
becomes
contain
embryo
grows to
new plants
pregnant
develops to
baby
needs
parental care
methods are
called
contraceptive
methods