1 | P a g e

Cells Reproduction and Inheritance

Cells

Cells are the tiny building blocks that make up all living things.

Living things can be unicellular or multicellular.

Unicellular = _______organism made of only 1 cell_

Multicellular = ____organism made of multiple/many cells_____

Cells are measured in µm.

1mm = _1000_ µm

The Microscope

See PPoint for completed diagram

Lens Colour Eyepiece

Magnification

Lens

Magnification

Total

Magnification

Small

Medium

Long

S2 Biology 3

2 | P a g e

Objects viewed under a microscope look much bigger but they also look slightly

different to the actual object.

The letter P as it looks on the slide:

The letter P as you look down the eyepiece lens:

Describe the 2 differences:

1. __Upside down_______________________

2. __back to front______________________________

Make up more slides to view and draw what you see below, remember to note the

object and the magnification used.

Magnification = x _____

P

P

3 | P a g e

Examining Cells

Animal Cell Plant Cell Bacterial Cell Yeast Cell

X _____ X_____ X______ X______

In order to be able to view cells under a microscope a stain must be added.

Cell Type Stain Used Colour of Stain

Animal methylene blue blue

Plant iodine orange/brown

Bacteria nigrosin black

Yeast methylene blue blue

Cell Structure

__yeast__ Cell __bacterial__ Cell

__plant_ Cell __animal__ Cell

4 | P a g e

Cell Parts and Functions

Cell Part Function Found in

Nucleus

contains genetic information

Plant

Yeast

Animal

Cell Membrane

allows substances to pass into and

out of the cell

Plant

Yeast

Animal

Bacterial

Cytoplasm

site of chemical reactions

Plant

Yeast

Animal

Bacterial

Cell wall

holds plant cell shape/structure

Plant

Yeast

Bacterial

Chloroplast

site of photosynthesis

Plant

Vacuole

contains dissolved sugars/salts

Plant

Yeast

Plasmid

contains genetic information

Bacterial

5 | P a g e

Specialised Cells

There are many different types of animal and plant cell. They are called

specialised cells and all have very different jobs.

Although all animal cells and all plant cells have the same basic parts, they can

have special features that make them good at their job.

Specialised

Cell

Plant or

Animal?

Diagram

Function How structure

makes it good at

its job

Red blood

cell

animal

carry oxygen Biconcave shape

increases surface

area

No nucleus – more

space for oxygen

Haemoglobin –

carries oxygen

Leaf

palisade

cell

plant

photosynthesis has lots of

chloroplasts for

photosynthesis

large surface area

to maximise light

absorption

Nerve cell

animal

carry electrical

messages

long and thin to

carry messages all

around body

insulated for quick

transfer of

electrical messages

Root hair

cell

plant

absorbs water large surface area

maximises water

absorption

Specialised Cells for Reproduction

In order for animals to reproduce, they must produce specialised cells called

sperm and eggs.

These specialised cells are known as sex cells or gametes.

6 | P a g e

Male gamete = ___sperm___

Female gamete = __egg_____

The Sperm Cell The Egg Cell

Diagram

Site of production

testes ovary

Size

very small larger

Number

half a billion

1500 per second

one per month

Mobility

tail to swim cannot move independently

Fertilisation

Fertilisation is when the nucleus of an egg cell fuses with the nucleus_ of a

sperm cell.

Site of fertilisation = __oviduct_

7 | P a g e

Only 1 sperm can fertilise an

egg cell.

The sperm cell has _50_ % of

the genetic information in its

nucleus

The egg cell has 50_ % of the

genetic information in its

nucleus

8 | P a g e

See PPoint for completed diagrams

9 | P a g e

Embryo Development

Stages of Fertilisation

See PPoint for completed diagram

After fertilisation the tiny ball of cells implants into the wall of the uterus and

begins to develop.

10 | P a g e

Developing Embryo

Size _o.1mm_

Important developments:

__Cells divide and becomes a blastocyct.

Moves along oviduct____

___________________________________

Size ___0.5-0.7mm___

Important developments:

Cells implant into uterus lining

Size __3mm___

Important developments:

___arms and legs grow longer. Lungs begin to

develop_____

___________________________________

Size ___16cm__

Important developments:

baby can hear, swallow and move

around_______

Size __50cm__

Important developments:

head hair coarse, fingernails longer____

11 | P a g e

Effect of Chemicals on Developing Embryos

Chemicals like tobacco and alcohol can have effect the growth and development

of an embryo.

Complete the graph below to show the effect of smoking on an unborn baby

Smoking Status of Mother Average weight of baby at birth (g)

Non smoker 340

Smoker who gave up before pregnancy 335

Smoker throughout pregnancy 315

Describe the effect of smoking on the average weight of babies at birth.

Smoking decreases the average birth weight of babies

___________________________________________________________

300

Ave

rage

wei

ght

of b

aby

at b

irth

(g)

12 | P a g e

Inheritance

Genetic information is passed on from parents to their offspring (children)

through genes found on DNA. This happens during fertilisation.

Information about characteristics like hair colour, height, blood type and eye

colour are all passed on by parents. This is called inheritance.

The characteristics we can see in an organism is called its phenotype.

For every characteristic we have, we receive 2 copies of the gene that controls

this. One copy from mum and the other from dad.

Inheriting Eye Colour

The gene for eye colour can take many different forms, blue, green, brown,

hazel etc.

Mum X Dad

Blue eyes Brown eyes

Child

The child has received one gene for blue eyes from dad and one gene for brown

eyes from mum.

The child’s eyes will be __brown__

The dominant gene for eye colour is __brown__

Dominant traits are always shown in the organisms’ phenotype.

My phenotype

13 | P a g e

Characteristics and Identification of Organisms

An organism’s phenotype can help it to be identified.

Scientists use keys for identification.

Branching Keys

A branching key is a diagram with questions that you answer and follow to

identify the organisms within it.

Use the key to identify the 2 organisms below:

____Paula__

___Tom____

Yes

Do its wings join

at the bottom?

Betsy Tom Paula Fred

Mike Scott

6 legs

14 | P a g e

DNA Structure and Function

DNA a like special code that is found on chromosomes in the nucleus of cells.

In bacteria, the plasmid is made of DNA.

It contains many regions called genes that control an organisms characteristics.

Each gene tells your body how to make a particular protein.

DNA Profiling

DNA profiling is when the special code on a person’s DNA is collected and

analysed. It can be used for many different reasons.

Uses of DNA

DNA is unique so no one’s DNA is the same. This makes DNA very useful for

identifying certain individuals.

DNA Use Description of Use Advantages Disadvantages

Forensics

DNA sequences can be

collected as evidence

from crime scenes and

can be compared with

DNA from victims and

suspects to find a match

Identifies criminals Time consuming,

criminal’s DNA must

be on record in

order to be found a

match

Paternity Testing

DNA from parents and

children can be

sequenced and compared

to look for similarities

Identifies

biological parents

of children

Someone might not

realise that their

parents are not in

fact their biological

parents so could be

upsetting to find out

Disease

Detection

DNA of individuals can

be sequenced and

checked for sequences

that cause/could cause

certain inherited

diseases

Can allow people to

prepare for illness

or disease/can help

future and family

planning/allows

people to take

preventative

measures

Some people might

not want to know if

they are going to

develop a

disease/might

affect life insurance

or mortgages

15 | P a g e