Download National 5 Biology Unit 2 – Multicellular Organisms

National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 1 – Cells, tissues and organs
Learning Intentions


To extend knowledge on multicellular
organisms.
To develop knowledge on how cell structure
is related to function.
Success Criteria



I can state that multicellular organisms have
more than one cell type and are made up of
tissues and organs.
I can recognise that the structure of a cell is
related to its function.
I can give examples of how cell structure is
related to its function.
Multicellular organisms

Can you think of any examples of
multicellular organisms?
Multicellular organisms
What are multicellular organisms?

Multicellular organisms have more than
one cell type and are made up of tissues
and organs.
Multicellular organisms
cells
tissues
organs
organisms
Multicellular organisms - cells

Multicellular organisms are made up of
many types of cell.

Can you think of any cell types in the
human body?
Cells in organs

The cells in organs are specialised for
their function.
What is the function of the
following cells and why are they
suited to their function?
Sperm cell
Red blood cell
Activity 1:
Collect a worksheet with the
diagrams above.
Make notes on their structure and
function in your jotter.
Root hair cell
Activity 2

Use relevant resources to find out 3
more examples of cells where structure
is related to function.
Cell type
Structure
Function
Activity 3 / extension

Look at different cell types under the
microscope and relate their structure and
function
National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 2 – Cells, tissues and
organs
Learning Intentions



To extend knowledge on multicellular
organisms.
To develop knowledge on the formation of
tissues from cells in multicellular organisms.
To develop knowledge on the formation of
organs from tissues.
Success Criteria




I can state tissues are made from groups of
cells with similar structure and function.
I can give examples of how cells form
tissues in multicellular organisms.
I can state that tissues form organs in
multicellular organisms.
I can describe organ systems, recognising
the cells, tissues and organs involved.
Multicellular organisms

Can you remember what a multicellular
organism is?

Multicellular organisms have more than one
cell type and are made up of tissues and
organs.
Multicellular organisms
cells
tissues
organs
organisms
Multicellular organisms - tissues

Tissues are made from groups of cells with
similar structure and function.
Example 1 – nerve tissue

Nerves carry
impulses (e.g.
sensation and
motion) between
the brain or spinal
cord and other
parts of the body.
Nervous tissue

Nerve tissue is
made up of nerve
cells (neurons).

The nervous system
also contains glial cells
which provide support
and protection for
neurons. They are
essential for the proper
operation of the
nervous tissue and
nervous system.
Nervous cells
Nervous tissue
Multicellular organisms
cells
tissues
organs
organisms
Multicellular organisms - organs

Organs or organ systems are groups of
tissues working together.

Organs perform different functions.

What do you think the organ system would
be in the nerve cell example?

The nervous system
Nervous cells
Nervous tissue
Nervous
system
Activity 1


Use the worksheet to construct this image in
your jotter.
Add the appropriate labels.

BBC Science & Nature - Human Body
and Mind - Nervous System Layer
Example 2 – the circulatory system

Activity 2: Use the worksheet to show the
connection between the cells, tissues and
organs in the circulatory system.
Tissues in the circulatory system

What do you think the functions of the
cardiac, nerve and blood tissues are in the
circulatory system?
Tissues in the circulatory system



The cardiac muscle tissue contracts, making
the heart pump.
The nerve tissue brings messages that tell
the heart how fast to beat.
The blood tissue is carried from the heart to
other organs of the body.
Activity 3
Questions relating to the circulatory system
activity
1) What is the function of red and white blood
cells?
2) What do the words oxygenated and
deoxygenated mean?
3) What are the functions of the valves in the heart
diagram?
4) How many chambers does the heart have?
What are they called?
Activity 3 - answers
Answers relating to the circulatory system activity
1) What is the function of red and white blood cells?
- Red blood cells transport oxygen around the body
- White blood cells are involved in the immune
response to infection
2) What do the words oxygenated and deoxygenated
mean?
- Oxygenated – saturated with oxygen / high oxygen
- Deoxygenated – low oxygen
Activity 3 - answers
Answers relating to the circulatory system activity
3) What are the functions of the valves in the heart
diagram?
- Prevent the backflow of blood
4) How many chambers does the heart have? What
are they called?
-4
- Left ventricle, right ventricle, right atrium, left
atrium
National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 3 – Growth and development
of organisms
Learning intentions


To extend knowledge on growth
To explain the growth and development of a
variety of animals
Success criteria


I can state that growth is the irreversible
increase in cell number which leads to an
increase in mass or length.
I can compare the growth and development
of a variety of animals.
What is growth?


Growth is the irreversible increase in dry
mass of an organism and is normally
accompanied by an increase in cell number.
Growth involves the production of new
structures.
Why is dry mass used and not fresh
mass?

Fresh mass is less reliable as an indicator of
growth because there will be changes in an
organisms water content which will affect
their mass.
Activity - animal and plant
development


From the sheets choose two plants and two
animals you would like to research.
Discuss the terms in the sheet as a class
prior to starting the task.
National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 4 – Seed germination
Learning intentions


To extend knowledge on investigations
To extend knowledge on the conditions
required for germination
Success criteria




I can describe an experiment which shows
that seeds need water for germination.
I can describe an experiment which shows
that seeds need oxygen for germination.
I can describe an experiment which shows
that seeds need warmth for germination.
I can describe an experiment which shows
that seeds can germinate in the dark.
Recap questions




What are the 3 parts of a seed?
What is germination?
What conditions do seeds need to
germinate?
What does the word optimum mean?
Group task – What conditions do
seeds need to germinate?

The class will be split into groups to allow all
investigations to be covered (temperature,
oxygen, water and light)

In your group you will plan an investigation
on your chosen factor.

Try and come up with a method on your
own. (There are support sheets available if
required).
Your investigation and write up
must include:







Aim: What variable factor are you investigating?
Hypothesis: What do you predict will happen?
Method/Diagram: brief description of what you are
doing and how you will alter your variable factor
Results: Construct a table
Graph: Use your results
Conclusion: What did your results show?
Evaluation: How could you improve the
experiment? Why is more than one seed used?
Why is only one variable factor investigated at one
time?
National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 5 – Conditions needed to
maintain growth and development in
humans
Learning intentions



To explain what is needed by humans for
growth and development.
To extend knowledge on the uses of food by
the body.
To develop knowledge on metabolism.
Success criteria






I can state that food is a source of fuel and
building materials.
I can state that food helps fight disease.
I can identify the different food groups and
their uses by the body.
I can explain what vitamins and minerals are
needed for.
I can explain what water is used for in the
body.
I can explain what is meant by metabolism.
Activity:


Collect an information booklet – read
through the information and answer the
questions.
Do not lose these sheets – they are your
notes and will be needed for revision.
Extension activity

Research and present information on either
a vitamin or mineral deficiency

Points to think about:
What the vitamin/ mineral is needed for
Why someone may become deficient
The effect of the deficiency on the body
The effects on growth of deficiency in a diet




How do chemicals and radiation
affect growth and development


You have 30 minutes to find out ways in
which radiation and chemicals can affect
growth and development.
Present the information in your jotter e.g.
spider diagram, table or note form.
Homework


Produce a poster or piece of writing on
commercial plant growing.
Think about what it is and why it is done.
National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 6 – Stem cells
Learning intentions

To extend knowledge on stem cells.
Success criteria


I can state that stem cells are the site of
production of specialised cells in animals.
I can state that stem cells are involved in
growth and repair.
What are stem cells?



Stem cells are the sites of production of
specialised cells in animals.
They have the potential to become different
types of cell.
They are involved in growth and repair.
Investigating stem cells


Use a variety of media to investigate the
potential uses of stem cells.
Think about what ethical issues are
associated with their use.
National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 7 – Meristems
Learning intentions

To develop knowledge on meristems
Success criteria




I can state that meristems are areas of non
specialised cells in plants
I can state that meristems are involved in
plant growth
I can state that meristems produce cells that
can become specialised into any plant cell
type
I can state that meristems are the only
points in plants where cell division happens
What are meristems?



Meristems are the sites of production of
non-specialised cells in plants.
These cells have the potential to become
any type of plant cell and contribute to plant
growth.
They are the only sites for cell division in a
plant.
Where are meristems found in the
plant?

Meristems are present at root and shoot
tips (apical meristems) and lateral buds
(lateral meristems)
Collect a
diagram and
highlight the
lateral and apical
meristems.
Lateral buds



Cells at root and shoot
tips undergo rapid
mitosis and cell division
producing new cells
New cells expand by a
process called
Xylem and
elongation
phloem
New cells produced
can differentiate to form
specialised tissues
such as xylem or
phloem
Differentiation
Elongation
Mitosis
Lateral
meristems
Vascular
Bundle
Xylem
Cambium
Phloem
• Lateral meristems consist of cambium cells.
• These cells are situated in vascular bundles
between xylem and phloem tissue
Collect and label a diagram
of the lateral meristem.
Secondary Thickening ( growth )
Xylem
Cambium
Phloem
Vascular Bundle
Year 1
Year 2
Rings of
Xylem
Year 3
Year 4
• Xylem is produced every year leading to the
formation of annual rings
Year 4
Poor year
Cambium
Year 3
Summer into autumn Xylem
Good year
Year 2
Spring into summer Xylem
Year 1
Size of annual rings
•
•
•
Spring into Summer – large thin walled xylem vessels
allow for increased flow of water and minerals.
Summer into Autumn – small thick walled xylem
provide greater support.
The width of each ring is dependent upon growing
conditions present during that year.
a. Wider rings are produced by warm or wet
weather
b. Narrow rings are produced by cold or dry
conditions.
National 5 Biology
Unit 2 – Multicellular Organisms
Lesson 1 – Sexual and asexual
reproduction in plants and animals
Learning Intentions

To develop knowledge on asexual and
sexual reproduction in plants and animals.
Success Criteria



I can explain sexual and asexual
reproduction.
I can give examples of sexual and asexual
reproduction in animals.
I can give examples of asexual and sexual
reproduction in plants.

Reproduction is the process of producing
new individuals or offspring.

It is essential to ensure a species continues
to survive.
Living things reproduce by one of two methods
 Sexual reproduction
 Asexual reproduction
This type of reproduction requires two parents who
pass on genes in sex cells. These cells fuse
together at fertilisation and develop into new
offspring.
 This results in offspring with a mix of inherited
characteristics.
 The parents are usually a female and a male, but
not always.

There are two types of fertilisation:
Internal fertilisation
External fertilisation
 The
eggs and sperm are deposited outside
the body and the sperm moves towards the
egg.
 This
fertilisation is used by animals who
reproduce in water.
e.g. fish, amphibians, crustaceans and
molluscs
 The
eggs and sperm meet inside the body.
 The male usually deposits the sperm inside the
female.
 This type of fertilisation is used by animals who
reproduce on land.
e.g. mammals, reptiles, birds, insects, spiders
Fertilised eggs either develop inside or
outside an animals body.
 Research the fertilisation and development of
the following organisms.

Example of Animal
mammal
reptiles
birds
Invertebrates
Amphibians
Fish
Type of fertilisation Type of
development
Parental care
Example of Animal
Type of fertilisation Type of
development
parental care
mammal
internal
internal
yes
reptiles
internal
external
no
birds
internal
external
yes
Invertebrates
internal
external
no
Amphibians
external
external
no
Fish
external
external
no

These animals have both female and male sex organs

They can change sex during their life from one gender into
the next
 This resolves the problem of finding mates
Examples
Snails, clown fish, earth worms

Sexual reproduction introduces new gene
combinations into a population.

A species is more likely to survive sudden
changes in the environment because some
individuals will have adaptations to the new
conditions.
Offspring are produced from only one parent.
 The offspring only inherit the genes of that
one parent so there is no variation.
 It does not involve sex cells.
 The offspring will be an exact genetic copy of
the parent.


In animals there are 5 main methods that allow
animals to reproduce asexually
Budding
 Fragmentation
 Regeneration
 Parthenogenesis
 Binary fission

 Offspring
grow out of or within the body
of the parent e.g. Hydra, yeast,
sponges
 The
body of a parent can
break into distinct pieces
each of which can produce
an offspring e.g. Planarian
 Piece
of the parent can detach and it
can grow into new individuals
e.g. Starfish
 Development
of an egg that has not been
fertilised e.g. Shark, boa constrictor, stick
insect, bee wasp, ant, whiptail lizard, komodo
dragon
 Single
cell replicates and divides into
two identical cells e.g. bacteria
No need to waste energy moving to find a mate
 Numerous offspring are produced without
wasted energy and time



They would all share a genetic weakness
If a stable environment changes then no
individual would have the adaptations
needed to survive
There a two main methods that allow plants
to reproduce sexually.
 Spores
 When Ferns and Bryophytes (moss and
liver worts) reproduce they make spores
from which a new plant grows.
 Seeds
 When flowering plants reproduce they
make seeds from which a new plant
grows.

•
It introduces new gene combinations into a population.
•
Increases variety of some characteristics.
•
A species is more likely to survive sudden changes in the
environment because some individuals will be able to
survive.
•
Produces seeds or spores that can stay dormant until
conditions are suitable for growth.
•
Plants are well distributed so less competition for resources
between offspring e.g. water, light & space.

This produces offspring that inherit genes
from only one parent.

This results in offspring genetically identical
to the parents.

In plants this type of reproduction is a also
called vegetative propagation.

There are three main
methods that allow
plants to reproduce
asexually.
Runners
 Bulbs
 Tubers

Runners are side stems which produce
offspring at various points. The clones receive
food from the parent until they are fully
developed.
Tubers are underground stems swollen with food.
New plants grow from the tubers using the energy
stored in the tuber in the form of starch.
Bulbs


Bulbs are a leaf
bases swollen with
food.
New plants grow
from these using the
stored food for
energy for growth.
Activity/extension




Carry out various propagation
techniques with various plants:
Seeds
Cuttings
Bulbs
Commercial uses of plants



Research the commercial uses of plants.
Feedback to the class.
Use the feedback from everyone to create
your own notes.
National 5 Biology
Unit 2 – Multicellular Organisms
Lesson 2 – Sexual Reproduction in
detail
Learning Intentions



To extend knowledge on reproduction
To develop knowledge on the terms diploid
and haploid
To develop knowledge on the term gonads
Success Criteria




I can state that body cells are diploid.
I can identify the gametes and the site of
gamete production in plants and animals.
I can identify the term haploid.
I can explain how the fertilisation of haploid
gametes produces a diploid zygote.
Body cells

What do we mean by a body cell?

A body cell is every cell in the body except
from the sex cells.
Body cells

How many
chromosomes does
a human body cell
have?

46
Body cells

How many of each
chromosome are
present in the
diagram?
Body cells

There are 2 copies of each chromosome in
every body cell (including 2 sex
chromosomes).

23 pairs of 2 = 46 chromosomes in every
body cell that is produced.

Body cells are known as diploid cells.
(Di = 2)

Activity 1 - Chromosomes in organisms


Different numbers
of organisms have
different numbers
of chromosomes.
Research the
following
organisms and
complete the
table.
Organism Number of
chromosomes
Dog
Human
Donkey
Elephant
Rabbit
Snail
Cabbage
Chromosomes in organisms - answers
Organism
Dog
Human
Donkey
Elephant
Rabbit
Snail
Cabbage
Number of
chromosomes
38
46
62
56
44
24
18
Sex cells


Sex cells are known as gametes.
The gametes in animals are the sperm and the
egg
nucleus
Tail
cytoplasm
Cell
membrane
Activity 2

Collect and label a diagram of the sperm
and egg.
Gametes

The cells that produce the gametes are
known as gonads.

Do you have any idea what the gonads are
that produce the sperm and the egg?
Where are
sperm
made?
Sperm are
made in the
testes
Where are
eggs made?
Eggs are
made in the
ovary
Activity 3


Collect the diagrams of the male and female
reproductive organs.
Highlight the parts where gamete production
takes place.
Gamete formation in plants
• Flowers are the sexual organs of plants
• Both male and female reproductive organs are
usually found on the same flower
Gamete formation in plants
•Male gonad = anther
•Male sex cell = pollen
• Female gonad = ovary
•Female sex cell = ovule
containing the egg
Activity 4

Collect and label the diagram of the flower.

Highlight the male and female gonads and
sex cells.
Activity 5 – flower dissection
Flower Dissection .pdf
Sex cells

Earlier we learnt that normal body cells have
46 chromosomes and that they are diploid.

Sex cells (gametes) only have 23
chromosomes and are said to be haploid.

Why do you think gametes only have 23
chromosomes and not 46?
Why do gametes have 23
chromosomes?

This is because the 23 chromosomes from
both the sperm and egg fuse together
during fertilisation to give a zygote with 46
chromosomes.
23
Sperm with
single set of
chromosomes
Egg with single set
of chromosomes
23
Fusion of
nuclei
46
Zygote with double
set of chromosomes
National 5 Biology
Unit 2 – Multicellular organisms
Lesson 1 – Variation
Learning intentions


To develop knowledge on inheritance
To develop knowledge on discrete and
continuous variation.
Success criteria




I know that combining genes from separate
parents contributes to variation within a
species
I can give examples of inherited
characteristics
I can define and recognise discrete variation
and give examples
I can define and recognise continuous
variation and give examples
What is genetic variation?

Genetic variation refers to the variety of genes
in a population.

Combining genes from separate parents
contributes to variation within a species
What is genetic variation?

Humans vary in numerous characteristics e.g.
eye colour and hair colour because they have
different genes.

These genes are inherited from their parents.

What other inherited characteristics can cause
variation within populations?
Inherited characteristics







Hair type
Hand size
Height
Petal colour
Coat colour
Dimples
Tongue rolling
Variation

Variation can be categorised into two types:

Discrete variation
Continuous variation

Discrete variation



Discrete variation refers to differences in
characteristics that have a defined form.
You can think of it as being either/or.
(E.g. Your earlobes are either attached or
they are not. You can either roll your tongue
or you cannot You either have brown hair or
you do not).
Information is usually presented in a bar
graph or pie chart.
10
Number in
class
5
green
blue brown grey
Eye colour
Activity 1 – as a class find out the number of
people with each eye colour. Construct a bar
graph of the results and answer the questions.
Eye colour
Number of people
Blue
Brown
Green
Grey
1. What percentage of people have blue eyes?
2. What is the ratio of brown eyes to grey eyes?
3. Write down 5 examples of discrete variation.
Continuous variation




Continuous variation exists in a range of
forms.
There are usually a variety of figures for the
characteristic.
E.g. Height and temperature.
Information is usually presented in a line
graph or histogram.
30
Number
in Year
25
20
15
10
5
120- 125- 130- 135- 140- 145- 150- 155- 160124 129 134 139 144 149 154 159 164
Height in cm
Activity 2 – construct your own histogram using the
heights from the people in your class
Height (cm)
120 -124
125-129
130-135
135-139
140-144
145-149
150-154
155-159
160-164
Number of people
Activity 3 – construct a line graph of the following
results and answer the questions.
Time (minutes)
0
Temperature (oC)
13
5
10
15
25
60
88
20
25
30
70
64
50
1. Explain the relationship between time and temperature
2. Calculate the percentage increase in temperature between 0 minutes and
15 minutes
3. Write down 5 examples of continuous variation.
National 5 Biology
Unit 2 – Multicellular organisms
Lesson 2 – Monohybrid cross
Learning intentions


To develop knowledge on the monohybrid
cross.
To develop knowledge on the terms
associated with the monohybrid cross.
Success criteria


I can explain and carry out a monohybrid
cross.
I can define the terms allele, phenotype,
genotype, dominant, recessive, true
breeding, homozygous and heterozygous.
Genetics

The way in which inherited characteristics are
passed on from parents to their offspring
follows a pattern.

The study of patterns of inheritance is called
GENETICS
Chromosomes
Genetic information passed on from parents to
offspring is carried on structures called
chromosomes which are found in the nucleus.
Chromosomes are usually only visible during cell
division when stained with a dye.
Genes and Alleles
Genes are part of chromosomes.
Each gene can exist in a number of different forms.
E.g. the gene for eye colour can be for brown or blue
or green or grey etc.
The different forms of each gene are known as
ALLELES.
Collect a copy
of the diagram
and add it to
your notes
Organism
Gene
Examples of
Alleles
Human
Blood group
A and B etc
Labrador Dog
Coat Colour
Black, Golden
Cat
Hair Length
Short, Long
Budgerigar
Feather Colour
Blue, Green
Cattle
Horns
Horns, Hornless
Pea Plant
Height
Tall, Dwarf
Maize
Grain Colour
Yellow, Purple
Genotype
• The type of genes that an organism possesses
is called its GENOTYPE.
Phenotype
The set of observable characteristics of an
individual resulting from the interaction of its
genotype with the environment.
Some characteristics and their
phenotypes
Organism
Characteristic
Body Colour
Fruit Fly
Wing Type
Hair Colour
Guinea Pig
Hair Type
Stem Length
Peas
Flower Colour
Phenotype
Grey
Black
Straight
Curled
White
Black
Smooth
Rough
Dwarf
Tall
Red
White
Dominance
Some phenotypes are dominant to others. It
is these characteristics you see even if others
are present
e.g. black hair is dominant to red hair.
+
=
The characteristic you do not see e.g. red hair would be called
recessive.
True-breeding
A true-breeding organism can be crossed with
another organism of the same kind and produce
off-spring with exactly the same characteristic
phenotypes.
+
=
True breeding individuals have only one type of allele
A homozygous individual possesses two of
the same kinds of alleles e.g. TT or tt (true
breeding)
A heterozygous individual possesses two
different alleles e.g. Tt
Examples of phenotype, genotype,
dominant and recessive
The b and B
represent
alleles.



Why is there two alleles present?
Why is the letter b or B used?
What phenotype would a person with Bb have?
Monohybrid cross

A cross between two parents different in
their phenotypes for one characteristic is
called a monohybrid cross.
Most characteristics that are controlled by a
single gene show discontinuous variation –
there are clear-cut phenotypes e.g. tongue
rolling, lilac or white flowers in pea plants
P
Represents the parents
F1
Represents the first generation
F2
Represents the second generation
A lot of important work in genetics has been
done by studying inheritance in fruit flies.
One characteristic which can be used to
illustrate inheritance is wing type in Fruit Flies.
These can be NORMAL or VESTIGIAL.
Normal wings
Fruit fly with
normal wings
Fruit fly with
vestigial wings
Wing type is controlled by a pair of genes.
Each gene can be one of two types of ALLELES.
N = normal wings
n = vestigial wings
Normal wing is dominant over vestigial wing.
Vestigial wing is said to be recessive.
Parent (P)
NN X nn
N
Gametes
F1 generation
n
All
Nn
Genotype all Nn
Phenotype all Normal winged
F1
generation
Gametes
Nn X Nn
N or n
We can work out
the chances of each
type of offspring
using a punnett
square.
N or n
N n
N NN Nn
n Nn nn
F2
Generation
N n
N NN
Nn
Normal Normal
n Normal
Nn nn
Vestigial
Genotypes
NN , Nn and nn
Phenotypes
Normal and Vestigial
Phenotype Ratio
3:1
Activity 1

Use the information you have learned so far
to complete the stages of the monohybrid
cross on the next slide.
Black mouse
Parent genotype
Gametes
F1 generation
Cross F1
Gametes
Punnett square
F2 generation
(genotypes)
F2 generation
(phenotypes)
Ratio
x
White mouse
Observed vs. predicted phenotypic ratios
•Monohybrid crosses always produce a 3:1 ratio in the
F2 generation. However, there is often a difference
between the observed and predicted figures.
•This happens because fertilisation is a random
process involving chance.
F2 Ratios by Experiment
Investigator
Number of
Yellow Seeds
Number of
Green seeds
Total
Ratio
Mendel
6022
2001
8023
3.01 : 1
Correns
1394
453
1847
3.08 : 1
Tschermak
3580
1190
4770
3.01 : 1
Hurst
1310
445
1755
2.94 : 1
Bateson
11902
3903
15806
3.05 : 1
Lock
1438
514
1952
2.80 : 1
Darbishire
109060
36186
145246
3.01 : 1
TOTALS
134706
44692
179246
3.01:1
Activity 2

Complete the monohybrid cross
worksheet.
National 5 Biology
Unit 2 – Multicellular organisms
Lesson 3 – polygenic inheritance and
family trees
Learning intentions


To develop knowledge on polygenic
inheritance.
To develop understanding on family trees
and the benefits they have.
Success criteria



I can define the term polygenic inheritance
and give examples.
I can use a family tree to work out the
phenotypes and genotypes of individuals.
I know that individuals with medical traits
can receive genetic counselling.
Polygenic inheritance

Most features of an individual phenotype are
polygenic and show continuous variation.

Polygenic inheritance is when a single trait
is controlled by two or more sets of alleles.
Example – skin colour

Many different
alleles exist for
each parent
therefore numerous
skin colours can be
visible in the next
generation.
Example – skin colour


What are the
possible genotypes
of the F2
generation? (you
do not need to write
down them all)
Each of these
genotypes
produces a slightly
different skin colour
Collect a copy of
the diagrams
showing skin
colour
inheritance
Family trees


What is a family tree?
A family tree is a diagram showing the
relationships between people in several
generations of a family.
Activity 1

Can you make
a family tree
for your own
family?
Genetic conditions

Family trees can be used to identify
individuals with a genetic condition.

A genetic condition is an illness caused by
abnormalities in genes or chromosomes.
Examples of genetic disorders

Colour blindness - the inability or decreased
ability to see colour, or perceive colour differences,
under normal lighting conditions.

Cystic fibrosis -affects the lungs and also the
pancreas, liver, and intestine. It is characterised by
abnormal transport of chloride and sodium across
an epithelium, leading to thick, viscous secretions.
Examples of genetic disorders

Haemophilia - a group of genetic disorders
that impair the body's ability to control blood
clotting.

Tay–Sachs disease - a rare genetic
disorder. It causes a progressive
deterioration of mental and physical abilities
that starts around six months of age and
usually results in death by the age of four.
How are the defected genes passed
on?



The mother and the father
in this family are both
carriers for a genetic
condition.
This means that they
have one defective copy
of the gene and one
normal copy.
They do not have the
condition because the
normal gene (in this case)
is dominant over the
defective one.
Family tree


Family trees can be
used to identify
individuals with a
condition within a
family.
It allows families to
see the risk that
any future children
have of having the
condition.
Activity 2 - Using a family tree



Imagine this was a
family tree for colour
blindness.
An affected individual
has the genotype bb
and a normal individual
has the genotype BB.
Work out the genotypes
and phenotypes for the
members of the family.
Genetic counselling

Genetic counselling is the process by which
patients or relatives, at risk of an inherited
disorder, are advised of the consequences and
nature of the disorder, the probability of
developing or transmitting it, and the options
open to them in management and family
planning.
Activity 3 – research (extension)



-
-
Choose a genetic condition
Prepare a powerpoint presentation on the
condition.
Include key aspects:
What is the condition
What causes it
How is it treated
Is it dominant or recessive
National 4/5 Biology
Unit 2 – Multicellular Organisms
Lesson 1 – Nervous control
Learning Intentions


To extend knowledge on nervous control.
To develop knowledge on the brain
structure.
Success Criteria





I can state that the nervous system is made
of the brain, spinal cord and nerves
I can state that the Central Nervous System
(CNS) is made of the brain and spinal cord
I know the functions of the cerebrum,
cerebellum and medulla
I know how information flows around the
body in sensory nerves, motor nerves and
relay nerves
I know that a synapse is a join between
neurones (nerve cells)
Communication


Internal communication is required for
survival of a multicellular organism.
Cells in multicellular organisms do not work
independently.
Co-ordination


Co-ordination in the body
involves the sense organs
gathering information (1),
It involves the Central
nervous system (2) and the
muscles (3). These must
work together efficiently to
bring about all the many
functions essential to life.
Human nervous system
The human nervous
system is composed of
three parts: the brain,
spinal cord and the
nerves.
The Central Nervous
System (CNS) is the
brain and spinal cord
Nerves
Nerves carry information from the senses to the
central nervous system and from the central
nervous system to the muscles
Collect and
stick in the
diagram.
Nervous system
The nervous system is composed of two
parts: the central nervous system
and the peripheral nervous system.
Nerve fibres
Central nervous system
The central nervous system
(CNS) sorts out information
from the senses and sends
messages to those muscles
which make the appropriate
response.
The CNS is composed of the
brain and the spinal chord.
Peripheral Nervous System
This is composed of the sensory
nerves and the motor nerves
which take and send messages
from the body.
It is electrical impulses
that move along the
neurons.
Sensory nerves


Receptors on the skin detect stimuli.
Sensory nerves then send messages to the
brain from the sense organs.
Motor Neurones
Motor neurones connect the brain to the body.
Messages are sent from the brain to the
muscles where a response happens.
Stimuli Receptors
CNS Motor nerves
Sensory nerves
Response
Response can be
a rapid action
from a muscle or
a slower response
from a gland.
Synapse


A join between two nerves is known as a
synapse.
It allows chemicals to transfer from one
neuron to another.
Reflex Arc
1)
2)
3)
The body responds
immediately to a
stimulus without
intervention from the
brain.
The sensory nerve
sends message to the
spinal cord
The impulse passes
through a relay neurone
The impulse is picked up
by a motor neurone
which transmits the
signal to the muscles.
A reflex arc
Reflex actions




These are rapid, involuntary and automatic
Conscious thought from the brain is not
required
They protect the body from harm
They may still work for a short time after an
animal has died
* Discuss human reflexes e.g. knee jerk.
Brain



The brain is a bundle of
nerve fibres segregated
into several different
regions:
Cerebrum – responsible
for memory, reasoning,
imagination and conscious
thought
Cerebellum – balance and
co-ordination
Medulla – rate of breathing
and heartbeat
Collect and label
the brain diagram
Activity

Complete the worksheet on terms relating to
the nervous system