What affects their distribution and how can we investigate it?

Organisms and their environment

B2.4

What do you need to survive?

Physical factors may affect the distribution of organisms, including:TemperatureAmount of lightAvailability of:

Oxygen Carbon dioxideWaterNutrients

Write these into your notes with a different example and organism for each one.

Organisms need resources!

Temperature affects the rate of an organism’s metabolism.

Some organisms cannot maintain a constant high body temperature.

They cannot tolerate extreme temperatures.

Temperature

But… Galapagos Marine Iguana

Nutrients such as nitrates are essential for the growth of plants and microorganisms.

If there is a low concentration of these nutrients, these organisms struggle to grow and survive.

Availability of Nutrients

Plants require light as an energy source for photosynthesis.

In low light intensities plants grow very slowly.

Light Intensity

All organisms require water.It is essential because chemical reactions that

occur inside and outside cells occur in solution in water.

In the absence of water, cells, and therefore organisms, die

Water Availability

Oxygen is essential for aerobic respiration.It can become limited in the soil, so plant roots

cannot grow and absorb mineral ions and water.

It can also become limited in water, so aquatic organisms struggle to respire and survive.

Oxygen Availability

Carbon dioxide is essential for photosynthesis.This can become limited in an environment

where there are many plants.This will reduce the rate of growth of plants.

Carbon Dioxide Availability

Organisms will be found in locations where the physical factors from the last slide suit them.

Organisms follow resources!

Different organisms are adapted to survive in different environments, so they don’t all compete for the same resources. The particular set of conditions that an organism is suited to is called its ‘niche’.

Define the following terms in as few words as possible, then find them for these numbers:

2 4 9 3 5 2 4 2 5

MeanMode MedianRange

A quick maths reminderMean: add up all the numbers

and then divide by the number of numbers (answer: 36/9 = 4)

Mode: the value that occurs most often (answer: 2)

Median: the "middle" value in the list of numbers when they are arranged in numerical order (answer: 2 2 2 3 4 4 5 5 9)

Range: the difference between the largest and smallest values (answer: 9 – 2 = 7)

There are two main kinds of data that we can gather for the daisies in this field:Qualitative: ‘there are lots of daisies in the field’Quantitative: ‘there are 5087 daisies in the field’

Quantitative data gives a specific measure for your subject, but qualitative data only gives a rough idea.Quantitative data is usually

more useful……why do you think this is?

Counting daisies

Physical factors may affect the distribution of organisms, including: water, light, nutrients, oxygen, carbon dioxide

and temperature

What have we learned?