Factors affecting population size - Miss Hanson's Biology...
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Biosphere SG Biology How it works?
Transcript of Factors affecting population size - Miss Hanson's Biology...
Biosphere
SG Biology
How it works?
The Biosphere Investigating an ecosystem
Sampling and other measurement techniques applied to the investigation of an ecosystem.
How it works Components of an ecosystem,
energy flow,
population growth,
controlling factors.
Control and management Intervention in the natural balance of an ecosystem;
using understanding to manage ecosystems.
Identification
Think of a species (plant or animal)
Write down a description of your
species on a piece of card.
Exchange the card with another
member of the class.
Could they identify the species you
have described?
Identification keys
Identification keys help us to identify plants and animals. Have a look at the samples of keys available in class.
The two types of key you could use are: Numerical key
Branched key
Complete the worksheet on identification keys
Food Chains
Watch the Scientific Eye video
making notes on food chains, and
factors affecting populations.
Food Chains and Food
Webs
Environment and Feeding
Definitions Herbivore:
An animal that eats grass and other green plants in a food chain;
Carnivore: A flesh-eating animal.
Prey: An animal hunted or caught for food
Predator: An organism that lives by preying on other organisms.
Definitions Primary consumer:
An animal that eats grass and other green plants in a food chain; an herbivore.
Secondary consumer: An animal that feeds on smaller plant-eating animals in a food chain.
tertiary consumer: An animal that feeds on secondary consumers in a food chain.
Population: All the organisms of the same species living in the same place at the same time.
Food Chains Food chains are one way of showing how
organisms interact. For example:
Grass Rabbit Fox
The arrows represent the flow of energy
(food) between organisms, it points from
the eaten to the eater.
All food chains start with plants, they use sunlight during photosynthesis to build up food (energy) stores, these are then passed on to animals.
Important terms: Plants are producers because they produce their own food
Animals are consumers because they eat food to obtain energy.
There are 3 types of consumer Herbivores eat plants
Carnivores eat other animals
Omnivores eat plants and animals
Organisms that breakdown dead plants and animals are called decomposers, e.g. fungi, bacteria and worms
Producer primary secondary tertiary consumer consumer consumer
PLANTS HERBIVORE CARNIVORE TOP CARNIVORE
Food Webs
When several food chains in a
habitat are studied, some organisms
appear in more than one.
This is because most animals eat
more than one type of food.
If food chains in a habitat are linked,
they form a FOOD WEB.
Food web for a single tree
Which are the primary and secondary
consumers in this photograph?
Competing for the same
niche
Biosphere
How it works?
Populations
Adaptations
Factors affecting population size
Populations
A population is a group of
individuals of the same species living
in a particular habitat at the same
time.
The number of individuals present in
the population will depend on how
they can interact with two types of
factor.
Populations
Living factors – food, disease,
predation, mates, effects of
humans, and competition
Non-living factors – water, oxygen,
carbon dioxide, temperature and
light
Competition for Resources Plants and animals compete for resources.
Plants often compete with each other for space, and for nutrients and water from the soil.
Animals often compete with each other for space, water and food.
Competition for Resources
There are two types of competition: Intra-specific – competition between individuals of the same species
Red deer stags fight to
mate with the females
Boobies compete for
nesting space
Plants compete for space, light,
water and nutrients.
Competition for Resources
Inter-specific – competition between individuals of different species.
Garden birds compete for
food in winter
Factors affecting population size
A population is a group of individuals of the same species living in a particular habitat.
Births and immigration increase the size of a population.
Deaths and emigration decrease the size of a population.
Factors affecting population size
The size of a population, may also be affected by:
The total amount of food and water available, if food supply is low, then individuals will compete for them.
Oxygen shortage can limit numbers in a population that lives in water.
Poisons can build up in the environment and limit population growth.
Factors affecting population size
List continued from previous page:
Predation will limit the prey population.
Disease can spread quickly through
large populations.
Climate – drought, flood and storms all
affect population numbers.
Lack of shelter
Competition for light
Population Graphs
For one species in good conditions
1
2
3
4
time
Number of
individuals
For one population in good condition
1. Slow increase as only a few individuals.
2. Sharp increase, good conditions for growth
3. Some factors start to slow down increase (e.g. lack of food).
4. Stable population (birth rate = death rate)
Predator-prey relationships
Animals that kill and eat other animals are called predators. The animals that they eat are called prey.
Predators are usually bigger and fewer in number than their prey.
List five things that make a good predator:
List five ways prey have adapted escape from predators:
The graph shows the relationship
between a predator and its prey.
List what is happening in each of
the stages 1 – 5 on the predator
prey graph.
1. The prey has plenty of food. It breeds and increases in number.
2. The increase in prey means that there is more food for the predator. So the predator breeds and increases in number.
3. There are now lots of predators so more prey will be eaten. The number of prey goes down.
Predator prey graph 4. There are now less prey for the predator
to feed on. Food will be scarce and
many predators starve.
5. With fewer predators, more prey survive
to breed. The prey numbers increase
The cycle continues…
Adaptation
The Biosphere
How it works?
Learning Outcomes
To explain the terms ecosystem,
habitat and community.
To understand that physical factors
affect animals living in an ecosystem
To be able to explain how animals
are adapted for survival in arctic
and desert conditions.
What is an Ecosystem?
The Environment An ecosystem is an environment where living organisms can survive.
The environment is made up of lots of different ecosystems, such as seashore, a wood or a river.
Each ecosystem is made up Habitats and Communities
Habitat - This is the place where the organisms live. It has the conditions that they need to survive.
Community – all the living organisms that live in the habitat.
Physical Factors Each ecosystem has a set of environmental factors.
Availability of water
Temperature - Few living organisms can grow outside the range of 0oC to 40oC.
amount of Light - photosynthesis in plants, animals need light for visibility.
Availability of carbon dioxide and oxygen
These factors vary according to the time of day and the time of year.
Adaptations
Living things adapt to their
environment.
Watch the video clip, and then try
to fill in the table explaining how the
creature is adapted to it’s
environment.
Adaptations in different
animals
Look at the animals on the
worksheet, for each one try to give
where it lives and an example of
how it is adapted for survival in its
environment.
Pupil Activity
Surviving in different environments.
Read all information carefully
Answer questions 1 - 9
Camel
designed for desert conditions
Big flat feet stop it sinking into the sand.
Short hair underneath the camel
lets heat escape.
Coarse wool on top of its body protects the camel from the sun.
A camel’s hump is a fat store. It can break down fat to release water.
A camel can drink large amounts of water. Its mouth is tough so that it can eat thorny plants like cacti.
Adaptations to water loss
a cactus in the desert Leaves reduced to spines – to reduce water loss
through stoma
Swollen stem
stores water
Wide spread root
systems to increase
surface area for absorption.
Camel – designed for desert conditions
Big flat feet stop it sinking into the sand.
Short hair underneath the camel
lets heat escape.
Coarse wool on top of its body protects the camel from the sun.
A camel’s hump is a fat store. It can break down fat to release water.
A camel can drink large amounts of water. Its mouth is tough so that it can eat thorny plants like cacti.
Adaptations to water loss - a cactus in the desert
Leaves reduced to spines – to reduce water
loss through stoma
Swollen stem
stores water
Wide spread root
systems to increase
surface area for absorption.
Class activity To draw labelled diagrams of a cactus, a camel and a polar bear which explain how they are adapted to their environment.
Use one side of your exercise book for each diagram, and labels.
Use the handouts to help you with the labels.
Commendations will be awarded for exceptional work!
Pupil Activity - extension
Environmental factors affecting life
Read all the information supplied on
the sheet carefully.
Answer questions 1 – 11 in full
sentences.
