B16: Adaptations, interdependence and competition

Habitat

Environment in which an organism lives

Population

Total no. of organisms of the same species living in the same geographical area

Community

Populations of all the diff species that live in the same habitat

What does a community contain?

All the living organisms in an environment

Biotic

Living organisms in an environment

Abiotic

Non living parts of an environment

Examples of abiotic parts of an environment

• Amount of water

• Minerals in the soil

Ecosystem

Both the biotic + abiotic parts of an environment and how they interact

To survive and reproduce, what do organisms require?

A supply of materials from their surroundings + other living organisms there

• Eg water, plants eaten

Why do living organisms need to compete with each other?

Resources needed to survive + reproduce are in short supply

Resources plants compete for

• Light

• Space

• Water

• Mineral ions in soil

Resources animals compete for

• Food

• Water

• Mates

• Territory

Interdependence

All of the different species in a community depend on each other

What does every animal depend on other living organisms for?

Food

• From animals or plants

What can some living organisms provide?

Shelter

• Trees shelter animals from the sun

What do plants depend on animals for?

• Bees- to spread their pollen

• Birds- to disperse seeds in their species

What happens if a species disappears from a community?

Affects whole community

Within a community what do each species depend on other species for?

• Food

• Shelter

• Pollination

• Seed dispersal

What happens if bees disappear from a community?

• Lots of plants don’t get pollinated

• → Plants can’t reproduce

• → Animals that feed on these plants run out of food → their populations fall

Stable community

All the species + environmental (abiotic) factors are in balance so that population sizes remain fairly constant

In a stable community do populations of species constantly change or remain fairly stable?

Fairly stable

Biotic factors that could affect an environment

1. Availability of food

2. Arrival of new predators

3. New pathogens

4. One species outcompeting another so the numbers are no longer sufficient to breed

What are all sources of food (plants and animals)?

Biotic factors

How can the biotic factor availability of food affect a community?

• All animals eat other living organisms

• Availability of food falls → no. of organisms in the community fall

How can the biotic factor arrival of a new predator affect a community?

1. Causes population of a prey species to fall

2. Affects existing predators: eg if competing for the same prey

Is competition between species a biotic or abiotic factor?

Biotic

What happens if a species is outcompeted?

Its population can fall sm →

• No.’s no longer sufficient to breed → species may become extinct

How can the biotic factor new pathogens affect a community?

Infectious disease emerges + spreads → can wipe out population of a species

Abiotic factors that could affect a community

1. Light intensity

2. Temperature

3. Moisture levels

4. Soil pH + mineral content

5. Wind intensity + direction

6. Carbon dioxide levels for plants

7. Oxygen levels for aquatic animals

How does light intensity affect plants?

All plants need light to carry out PS → LI too low → rate of PS falls → plants grow slower

How can plants growing slowly majorly affect a community?

Animals which feed on plants may not have enough food

How does temperature affect a community?

Temp of environment changes → distribution of species change

Examples of what could happen to animals and plants if the temperature changes

• A: migrate

• P: disappear

Why is water an important abiotic factor?

Animals + plants need it to survive

How does water affect a community?

Needed for survival → lots of animals adapted to low water levels

How does soil pH and mineral content affect plants?

• Many plants can’t grow on soil that is too acidic or too alkaline

• Plants need certain MI in soil

What do plants use nitrate ions in the soil for?

To make amino acids for proteins

How does wind intensity and direction affect plants?

Strong winds blowing inland from sea → causes plants to lose water

• Plants growing in sand dunes adapted to reduce water loss

How do gases like carbon dioxide affect plants?

CO₂ needed for PS → CO₂ level falls → PS rate decreases

How do gases like oxygen affect aquatic organisms?

O₂ needed for aerobic respiration→ dissolved O₂ falls (on hot days) → harmful to AO (eg fish)

Does the level of oxygen in the air stay fairly constant or change?

Fairly constant

What happens to levels of dissolved oxygen in water on hot days?

Falls

Adaptions

Organisms have features that enable them to survive in the conditions they normally live in

Types of adaptations

• Structural

• Behavioural

• Functional

Structural adaptations

Adaptations of body shape or body structure

Functional adaptations

Adaptations to body functions of an organism

Behavioural adaptations

Adaptations to the animals lifestyle or behaviour

Nocturnal

Mainly active at night

Extremophiles

Organisms adapted to live in v extreme conditions

Examples of extreme environments that extremophiles can live in

High:

• Temperature

• Pressure

• Salt concentration

Where do bacteria that are extremophiles live?

Deep sea vents

• Found on sea beds

V harsh conditions around deep sea vents

• High temp

• High pressure

What do ecologists use experimental methods eg transects + quadrats to do?

Determine the distribution + abundance of species in an ecosystem

2 ways of sampling

1. Random sampling

2. Sampling along transect

What is RS used to do?

Compare the no. of organisms in diff areas

What is needed for RS?

Quadrat

• Wooden / plastic square

How to use a quadrat?

• Place on ground

• Count no. of organisms inside quadrat

What can RS be used to sample?

• Plants

• Slow moving animals

In RS, where is the quadrat placed?

At random locations across the area

• Use random no.s

How many random locations need to be sampled in RS + why?

Large no

• More likely to get valid results

What happens if the quadrat is placed only 1 time?

May not give a sample that accurately represents the whole area

RS allows to compare?

No of species in diff conditions

Total population size equation

When is sampling along a transect

To investigate how the no. of species change as we move across a habitat