The document discusses several physical factors that can affect the distribution of organisms, including temperature, light availability, and availability of oxygen, carbon dioxide, water, and nutrients. It explains how each of these factors impact organisms - for example, that temperature affects metabolism, plants require light for photosynthesis, and all organisms need water. The document also introduces the concept of an organism's niche as the set of conditions it is suited to survive in.

1. B2.4
What affects their distribution and
how can we investigate it?

3.  Physical factors may affect the distribution of
organisms, including:
 Temperature
 Amount of light
 Availability of:
 Oxygen
 Carbon dioxide
 Water
 Nutrients
 Write these into your notes with a different example
and organism for each one.

4.  Temperature affects the rate of an organism’s
metabolism.
 Some organisms cannot maintain a constant high body
temperature.
 They cannot tolerate extreme temperatures.

6.  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.

7.  Plants require light as an energy source for
photosynthesis.
 In low light intensities plants grow very slowly.

8.  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

9.  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.

10.  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.

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

12.  Define the following  Mean: add up all the numbers
and then divide by the number
terms in as few words as of numbers (answer: 36/9 = 4)
possible, then find them
for these numbers:  Mode: the value that occurs most
often (answer: 2)
249352425
 Median: the "middle" value in
 Mean the list of numbers when they
are arranged in numerical order
 Mode (answer: 2 2 2 3 4 4 5 5 9)
 Median
 Range: the difference between
 Range the largest and smallest values
(answer: 9 – 2 = 7)

13.  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?

14.  Physical factors may affect the distribution of
organisms, including:
 water, light, nutrients, oxygen, carbon dioxide and
temperature