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Reproduction
In humans
MALE REPRODUCTIVE SYSTEM
Humans reproduce using sexual reproduction involving a man and a
woman
...
They have two functions:



to produce sperm (the male gametes or sex cells)
to make the hormone testosterone

Sperm duct and Glands; The sperm pass through the sperm ducts, and
mix with fluids produced by glands (seminal vesicles)
...
This mixture is called semen
...
A
ring of muscle ensures that urine and semen do not get mixed up
...
Ova are the female gametes or
sex cells
...

Oviducts; each ovary is connected to the uterus by an oviduct (fallopian
tube)
...
Every month, an ovum (egg)
develops and becomes mature, and is released from an ovary
...

Uterus and Cervix; the uterus is a muscular bag with a soft lining
...
The cervix is a ring of muscle at the lower
end of the uterus
...

Vagina and Urethra; the vagina is a muscular tube that leads from the
cervix to the outside of the woman's body
...
The opening to the vagina has
folds of skin called labia that meet to form a vulva
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It passes urine out of the body from the
bladder
...
The
changes take place gradually, usually between the ages of 10 and 16
...
During the process, the lining of the uterus is
prepared for pregnancy
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This is known as menstruation
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Stimulates the ovaries to
release oestrogen
Stops FSH being produced (so that only one egg matures in a cycle)
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Stimulates the pituitary gland
to release LH
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FERTILIZATION
Fertilisation is the fusion of the nucleus of a male gamete with the
nucleus of a female gamete, producing a new cell called a zygote
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DEVELOPING EMBRYO
After fertilisation, the newly-formed zygote divides repeatedly to
form a ball of cells called an embryo
...
After eight weeks of development, the embryo is called a fetus (also spelt ‘foetus’ but pronounced
the same)
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The placenta anchors the embryo
in the uterus
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These materials pass from one to the other by diffusion
...


In Plants
SEXUAL AND ASEXUAL REPRODUCTION
There are two types of reproduction - sexual reproduction and asexual reproduction
...

Only one parent is needed in asexual reproduction, and the offspring produced are genetically identical, eg
reproduction in bacteria, production of spores by fungi, and the formation of tubers in potatoes and bulbs in
daffodils
...
They produce male sex cells (pollen grains) and female
sex cells (contained in the ovules)
...

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Parts of a Flower;
STRUCTURE
Sepal
Petal
Stamen
Anther
Stigma
Ovary

FUNCTION
Protects the unopened flower
May be brightly coloured to attract insects
The male part of the flower, comprising an anther
attached to a filament
Produces the male sex cells (pollen)
The top of the female part of the flower, which
collects pollen grains
Produces the female sex cells (contained in the
ovules)

Insect pollinated flower

Wind Pollinated Flower
Grasses have wind-pollinated flowers
...

FEATURE
Petals
Scent and Nectar
Number of pollen Grains
Pollen Grains
Anthers
Stigma

INSECT POLLINATED
Large and brightly colored
Usually scented and with nectar
Moderate insects transport grains
efficiently
Sticky or spiky- Stick to insects
Inside flower stiff and firmly
attached- to brush against insects
Inside flower sticky- so pollen grains
can stick to it

WIND POLLINETATED
Small, often dull, green or brown
No scent or nectar
Large amounts, most pollen grains
are not transferred to other flowers
Smooth and light- Carried by the
wind
Outside flower, lose or long
filaments, to release pollen grains
Outside flower, feathery- to catch
pollen grains

FORMING SEEDS AND FRUIT
When a pollen grain lands on the stigma of a flower of the correct species, a pollen tube begins to grow
...
The nucleus of the pollen then passes along the pollen
tube and fuses (joins) with the nucleus of the ovule
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After fertilisation the female parts of the flower develop into a fruit:



the ovules become seeds
the rest of the carpel becomes the fruit

GERMINATION
A seed has three main parts:




embryo – the young root and shoot that will become the adult plant
food store – starch for the young plant to use until it is able to carry out photosynthesis
seed coat – a tough protective outer covering

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

Water-Lets the seed swell and the embryo start to grow
Oxygen- Needed for aerobic respiration
Warmth- Increases growth rate and enzyme activity (but very high temperatures denature enzymes)

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