4. Ecology and the Environment

Define biodiversity?

The variety of different species that live in an ecosystem.

How to investigate the distribution of organisms in their habitats and measure biodiversity using quadrats?

1. Select 2 different habitats.

2. Use same size qudrats.

3. Select coordinates at random in an area using random number generator.

4. Count number of different species(species richness).

5. Record how many organisms are in each species(species eveness).

6. Compare 2 habitats.

Role of nitrogen fixing bacteria in nitrogen cycle?

Turn atmospheric nitrogen gas into nitrogen compounds that plants can use.

Role of decomposers in the nitrogen cycle?

Breaks down proteins and urea and turns them into ammonia which forms ammonium ions in the soil.

Role of nitrifying bacteria in Nitrogen Cycle?

Turns ammonium ions in decaying matter into nitrates.

Role of denitrifying bacteria in Nitrogen Cycle?

Turns nitrates back into nitrogen gas.

State the 4 effects of deforestation?

Leaching

Soil erosion

Disturbance of evapotranspiration

Disturbance of CO2 and O2

How does deforestation effect leaching?

Trees take up nutrients from soil before they’re leached by rain, but return them to soil when leaves die.

When deforestation occurs nutrients get leached away but don’t get replaced leaving infertile soil.

How does deforestation affect the soil?

Tree roots hold the soil together.

So when deforestation occurs soil can be eroded by rain leaving infertile ground.

How does deforestation effect evapotranspiration?

Evapotranspiration is the process of water evaporating from Earth’s surface and from plant transpiration.

This water falls back as rain.

So when deforestation occurs evapotranspiration is reduced making climate drier.

How does deforestation effect the balance of CO2 and O2?

Trees take up CO2 by photosynthesis and slowly release its when they decompose.

When they’re cut down they release CO2 at once which disturbs carbon cycle and contributes to global warming.

Fewer trees means less photosynthesis takes place, releasing less oxygen causing oxygen levels to drop in atmosphere.