Term 3: Ecology and Genetics

Year 9 Summer term core questions :)

What are the levels of organisation of an ecosystem?

Individual organism, population, community, ecosystem

What is a population?

A group of individuals of the same species living together

What is a community?

All the living organisms in a habitat

What is an ecosystem?

The interaction of a community with the non-living parts of their environment

What is an abiotic factor?

A non-living factor affecting a community

Give seven examples of abiotic factors

Light intensity, temperature, moisture levels, soil pH, wind strength/direction, carbon dioxide levels (plants), oxygen levels (aquatic animals)

What is a biotic factor?

A living factor affecting a community

Give four examples of biotic factors

Food availability, new predators, new pathogens??, competition between species

What is interdependence?

Each species in a community depends on another for survival

Give four examples of interdependence

One species depends on another for food, shelter, pollination, seed dispersal

What is a stable community?

Where all species and abiotic factors are in balance, population sizes remain fairly constant

In a stable community, what happens to the population size of predators and prey?

They rise and fall in cycles

What are extremophiles?

Organisms living in very extreme environments

Give three examples of extreme environments.

High temperature, high pressure, high salt concentration

Give one example of an extremophile

Bacteria living in deep sea vents

How can population sizes and distributions be measured?

Using transects and quadrats

What is a line transect?

A line marked with a measuring tape which can be sampled at regular intervals

How can quadrats be used to estimate the number of organisms in an area?

They allow the numbers of organisms in a small sample of an area to be counted

What is variation?

Differences in characteristics of individuals in a population/species?

What factors can cause variation?

Genetic causes, environmental causes or a combination of both

What are genes?

Instructions for cells

What are genes made of?

DNA

How are genes passed on?

From parent to offspring through reproduction

What are genetic causes of variation?

The genes an individual inherits

What are environmental causes of variation?

The conditions in which an individual develops

What are mutations?

Changes in the DNA code

When do mutations occur?

All the time/whenever a cell divides

What causes genetic variation?

Mutations

How many mutations affect the characteristics of an individual?

Very few

What is biodiversity?

The variety of species of organisms in an ecosystem or on Earth

How does a high biodiversity help ensure stability of ecosystems?

Reduces the dependence of one species on another

What is the effect of decreased biodiversity on humans?

Decreased biodiversity threatens the existence of humans

What causes water pollution?

Sewage, fertiliser, toxic chemicals

What causes air pollution?

Smoke, acidic gases

What causes land pollution?

Landfill waste, toxic chemicals

What is the effect of pollution on plants and animals?

Can kill plants and animals and reduce biodiversity

Why do humans engage in large-scale deforestation?

To provide land for cattle, rice fields or biofuel crops

What is the main consequence of deforestation?

Reduction in biodiversity

What gases contribute to global warming?

Increasing carbon dioxide and methane

What are the main biological consequences of global warming?

Loss of habitats through flooding, reduction in biodiversity