This session is designed to review content covered in Core
Biology. Your exam is tomorrow.
We will cover a range of topics in the next 40 minutes. You are
advised to take notes. Annotate the handouts given to you.
You are expected to maintain exam conditions for the full time
the presentation is conducted. This aim of this is to develop your
understanding (& technique) in answering exam questions.
Any questions will be taken at the end of each topic.
CLASSIFCATION
Definition: The process by which scientists group living organisms. Organisms
are classified based on their characteristics.
The first thing are living things are classified by is their KINGDOM. There are 5 kingdoms…
What are the features of each of
these kingdoms?
Can be split further…
Reptiles
Birds
Mammals
Fish
Amphibians
Organisms can then be further
split according to:
Phylum
Binomial (universal)
Class
naming of species
Order
e.g: HOMO SAPIEN
Family
Genus
Species
Genus
Species
Oxygen enters bloodstream
and diffuses into the lungs
Controls the activity of the cell/ contains
genetic material.
Chloroplasts contain chlorophyll, these
are involved in the process of
photosynthesis.
When 2 different species
interbreed to produce
infertile offspring.
Explain the features of each of the 5 kingdoms (6 marks)
For this question, you will need to:
- Name the 5 kingdoms.
- Give features of each kingdom & explain these. For example:
“ We can classify all living organisms into 5 kingdoms, these are: animalia, plantae,
protist, prokaryote & fungi.
The Animalia kingdom is made up of organism which are multicellular and all of these
cells have a nucleus. The Animalia kingdom does not have cell walls or chloroplasts. All
organisms are heterotrophic feeders”.
Outline the characteristics of the 5 types of vertebrates (6 marks)
For this question, you will need to:
- Name the 5 animal groups.
- Give features of each. For example:
“ The 5 groups of vertebrates are: birds, fish, amphibians, reptiles and mammals. All of
these groups have their own characteristics.
Mammals have fur/hair to keep warm, they have mammary glands to feed their young.
They are warm blooded, this means they can regulate their own body temperature. They
use lungs to breathe with. They carry out internal fertilisation give birth to live offspring
What is
Darwin’s
theory?
Natural selection (Darwin’s theory)
The theory of evolution states that over time all the different species have
evolved from simple life forms.
Define the terms:
Natural selection: A process where organism suited to an environment are able to survive and reproduce.
Species: A group of organisms that are able to interbreed and produce fertile offspring.
What are the key points for the process of natural selection?
•Individuals in a species show a wide range of variation.
•This variation is because of differences in genes.
•Individuals with characteristics most suited to the environment in which they live are more likely to
survive and reproduce.
•The genes that allowed the individuals to be successful are passed to the offspring in the next
generation.
Individuals that are poorly adapted to their environment are less likely to survive and reproduce. This
means that their genes are less likely to be passed to the next generation.
Given enough time, a distinct new species will gradually evolve.
There is variation between the species of
giraffe., as most populations tend to
overproduce there will be competition
between the offspring.
Those with the desirable characteristic for
height will survive and reproduce, passing on
their gene for height.
Publishing results in scientific journals
Peer review
Taking part in scientific conferences
•
•
•
•
•
•
Competition between species
Survival of the fittest
Those that survive will pass on desirable
characteristic.
•
•
•
Thick skin to withstand high
temperature.
Bacteria.
Large surface area.
Sickle cell disease & Punnett squares
AN ALLELE IS AN ALTERNATIVE FORM OF A GENE. WE HAVE 2 ALLELES FOR EVERY CHARACTERISTIC, ONE
FROM EACH PARENT.
Learning checkpoint
Define the terms:
1) Which key terms can be used to describe the mum’s genes ?
Homozygous: a pair of chromosomes being made of two of the same alleles of a gene.
2) Which key terms can be used to describe the fathers genes?
Heterozygous: a pair of chromosomes being made of two different alleles.
3) Complete the punnet
square
Dominant: This allele determines the development of a characteristic
4) In percentage terms
what does the punnet square show?
Recessive: This allele only determines the characteristic if there is no dominant allele
5)What does this mean in terms of offspring phenotype?
present.
Example 1: A mum with blue eyes (bb) and dad with brown eyes (BB)
MOTHER
FATHER
B B
b Bb Bb
b Bb Bb
Father
bb
Parents:
Gametes:
b
BB
X
b
B
Mother
B
•
•
Muscle pain
Fatigue
B
b
B
BB
Bb
b
Bb
bb
1/4
25%
Heterozygous
DISEASE
Pathogen= disease causing microorganism.
Many pathogens are bacteria (causes cholera, food poisoning, dysentery & TB).
Other diseases are caused by viruses (influenza, measles, mumps and AIDS).
Some pathogens are fungi.
How do pathogens spread between people?
Water:
Water may contain bacteria
such as those that contain
cholera.
Airborne:
Influenza, cold viruses & TB
are spread in the air. E.g.
Coughs and sneezes.
Food:
Food may contain food
poisoning bacteria such as
Salmonella.
Contact:
Direct / indirect contact
Athletes foot fungus is usually
transferred to skin from
moist surfaces (e.g. Swimming
pool and shower)
Body fluid:
Pathogens such as HIV can
be transferred through
body fluids. E.g.: blood on a
shared syringe or during
intercourse.
Vectors:
Mosquitoes & houseflies.
What defences do we have against disease?
- CHEMICAL BARRIERS
- PHYSICAL BARRIER
The human body has various ways to
protect itself.
The skin is a physical barrier, it is a
protective layer that covers the whole
body and prevents pathogens from
entering.
1- Stomach has acid in to kill any
pathgens.
2- Tears have the enzyme lysosome.
Another physical barrier are eyelashes.these prevent any pathogens from
entering the eyes and causing
infection.
Thermoregulation
What happens when you are too
hot?
What happens when you are
cold?
• Vasodilation- Blood vessels widen to
allow heat to escape.
• Vasoconstriction- Blood vessels
narrow to keep heat in.
•Errector muscles relax- Muscle
attached to hair follicle relaxes, so
hairs lie flat. Helps to cool down.
•Erector muscles contract- hairs stand
up to trap a layer of insulating air.
•Sweating- When sweat evaporates
from the surface of the skin, it helps
to cool the body down.
•Shivering- Muscles contract and relax
rapidly to generate heat.
Pollution indicators
Carbon cycle
Exam tip:
Break down the carbon cycle into how carbon ENTERS &
theout
atmosphere.
Deforestation means less trees availableLEAVES
to carry
photosynthesis.
1.Carbon enters the atmosphere as carbon
from
respiration
and combustion.
If there is no photosynthesis dioxide
then the
amount
of carbon
dioxide
in the atmosphere will increase.
2.Carbon dioxide is absorbed by plants to
make carbohydrates in photosynthesis.
3.Animals feed on the plant passing the carbon
compounds along the food chain. Most of the carbon
they consume is exhaled as carbon dioxide, during
respiration. The animals and plants eventually die.
Sulfur dioxide causes acid rain. Acid rain is acidic and can
destroy rivers and lakes. This
means
less animals
anddown
plants are
4.The
dead organisms
are broken
able to live here.
by decomposers and the carbon in their bodies is
returned to the atmosphere as carbon dioxide.
Respiration
Eutrophication/ water
pollution
Plant hormones & uses of plant hormones
SHOOT
Phototropism
AUXIN is the plant hormone
found in the shoots, it causes
GROWTH (CELL
ENLONGATION). Sunlight
breaks down auxin.
Q2: Explain what the each
of shoots below show
Shaded
region
Q1: Explain why there is
more cell elongation in the
shaded region.
Geotropism
Geotropism
ROOT
Part of plant
Root
Shoot
A= Tips of shoot have been cut of, no auxin so no
growth of shoot.
Geotropism
Positive
Negative
Phototropism
Negative
Positive
B= Tips of shoot have a covering on, there is no
shaded region, therefore all shoots grow upwards.
C= The auxin in the shaded region has not been
broken down so cells elongate towards light source.