S1 – Cells and Reproduction Summary Notes

A cell is the basic unit of life. All living things are made from cells. Cells are so small
they can only be seen using a microscope. Plants and animals have different cells.
Animal cells contain three main components:
 Cell membrane – controls what enters and leaves
the cell
 Nucleus – control’s the cell’s activities
 Cytoplasm – where the cell’s activities take place
Plant cells contain six main components (three the same as
an animal cell and three others):
 Cell wall – give the cell shape and support
 Vacuole – stores a substance called sap
 Chloroplast – traps the Sun’s energy to make food

Our body contains lots of different types of cells. Many cells are adapted to carry
out a specific job. These are called specialised cells. Examples are red blood cells and
nerve cells.

The nucleus of a cell is extremely important as it control the cell’s activities.

Puberty is the period of time where we grow from a child in to an adult. Humans
undergo many changes (physical and emotional) during this time.
Emotional Changes
Boys
Girls
Mood swings
Mood swings
Independent
Independent
Take interest in
Take interest in
girls
boys
Physical Changes
Boys
Girls
Hair growth
Hair growth
Penis grows
Breasts develop
Testes grow
Eggs are released
Voice breaks
Growth spurt
More defined
muscles
Widening of hips
Growth sport
Menstration
begins

Reproduction is making a copy of something else. When animals reproduce they
make a “baby version” of themselves (e.g. humans reproduce to make a baby)

The parts of the body involved in reproduction are called the reproductive organs
The male sex cell is called a sperm. Sperm have a
head containing a nucleus and a tail
The female sex cell is called an egg
Eggs contain a nucleus and a large food
store

At fertilisation the head of the sperm cell enters an egg cell. The nucleus of the
sperm joins with the nucleus of the egg. At this point a zygote (the first cell of
an individual) is formed. At one point you were only one cell

Fertilisation occurs in the oviduct the fertilised egg divides into 2, 4, 8, 16 and so
on until it forms a ball of cells. This ball of cells then implants in the spongy lining
of the uterus. The developing embryo makes an organ called the placenta that
lets it exchange nutrients and waste with the mother.

Pregnancy lasts approximately 9 months. This is called the gestation period.

There are some risks to the developing embryo such as:

o
Smoking
o
Drinking alcohol
o
Drugs
These harmful substances can cross the placenta from the mother in to the baby.
However useful substances like antibodies can also cross the placenta.
S1 – Cells and Reproduction Practice Test
1. Copy and complete the below table:
Component
Nucleus
Vacuole
Cell membrane
(4 marks)
Function
Helps keep shape of cell
Stores sap
Found in
Plant and animal cells
Plant cells
Plant and animal cells
2. Name one physical change that occurs in boys during puberty.
(1 mark)
3. Name on emotional change that occurs in girls during puberty.
(1 mark)
4. Name female and male sex cells.
(2 marks)
5. Label the diagram of the male and female reproductive systems.
(2 marks)
6. Name two risks to embryonic development and explain why they are risks.
(2 marks)
7. Give an example of a specialised cell in the body.
(1 mark)
8. Where are the sex cells produced in males and females?
(1 mark)
9. What is the name given to the ball of cells formed during fertilisation?
(1 mark)