Download Organisms and their environment (Student Support)

Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
-1-
Biology workbook
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
Biology workbook
WORKBOOK 4 - ORGANISMS AND THEIR ENVIRONMENT
Living organisms form communities, and we need to understand the relationships within
and between these communities. These relationships are affected by external
influences.
Candidates should use their skills, knowledge and understanding to:
suggest reasons for the distribution of living organisms in a particular habitat
■ evaluate methods used to collect environmental data, and consider the validity of the
method and the reproducibility of the data as evidence for environmental change.
■
Subject content - Distribution of organisms
a) Physical factors that may affect organisms are:
■ temperature
■ availability of nutrients
■ amount of light
■ availability of water
■ availability of oxygen and carbon dioxide.
b) Quantitative data on the distribution of organisms can be obtained by:
■ random sampling with quadrats
■ sampling along a transect.
Suggested ideas for practical work to develop skills and understanding:
investigative fieldwork involving sampling techniques and the use of quadrats and
transects; which might
include, on a local scale, the:
– patterns of grass growth under trees
– distribution of daisy and dandelion plants in a field
– distribution of lichens or moss on trees, walls and other surfaces
– distribution of the alga Pleurococcus on trees, walls and other surfaces
– leaf size in plants growing on or climbing against walls, including height and effect of
aspect
■ analysing the measurement of specific abiotic factors in relation to the distribution of
organisms
■ the study of hay infusions
■ the use of sensors to measure environmental conditions in a fieldwork context.
■
Additional guidance:
Candidates should understand:
■ the terms mean, median and mode
■ that sample size is related to both validity and reproducibility.
1
2
Watch the Youtube clip: “Making the ideal habitat”:
http://clipbank/espresso/clipbank/servlet/link?macro=setresource&template=vid&resourc
eID=1672&taxonomyNodeID=727
Discuss the clip in terms of the requirements of the animals in the Zoo.
Make a list of the main physical factors which might affect organisms and give an
example in each case of what the effect might be:
-2-
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
Biology workbook
Light intensity / day length: affects growth of plants; can affect
reproduction of some animals, migration of some birds, and can
stimulate hibernation of some animals.
Temperature: affects growth of plants; can stimulate hibernation
of some animals.
Soil type: affects growth of plants; determines the types of plant
which grow, which determines the types of animal which live in a
habitat; can affect ability of animals to burrow.
Rainfall / water supply: affects growth of plants; determines the
types of plant which grow, which determines the types of animal
which live in a habitat.
(Also: wind; aspect; altitude.)
3
Discuss / revise quadrats & transects with your teacher
Read your textbook / support material on Biology fieldwork sampling techniques:
If possible, visit this website which describes sampling techniques.
http://www.habitats.freeserve.co.uk/howto.htm
a) Describe a) a quadrat and b) a transect & explain how you would use each to carry
out a random or systematic sample of plant species distribution on the school playing
field.
A quadrat is used to gain a random sample of plants in a habitat. It is
simply a square that is thrown randomly on some part of the ground. The
plants are then counted or their percentage cover estimated and the area of
the quadrat is then multiplied to find the estimated population of the area.
E.g. It can be used to estimate the population of daisies on the school
playing field by throwing 10 quadrats and counting the daisies or estimating
% cover.
A Line Transect. Systematic sampling is when samples are taken at fixed
intervals, usually along a line. This normally involves doing transects,
where a sampling line is set up across areas where there are clear
environmental gradients. For example you might use a transect to show the
changes of plant species as you moved from grassland into woodland.
A Belt Transect is similar to the line transect method but gives information
on abundance as well as presence, or absence of species. It may be
considered as a widening of the line transect to form a continuous belt, or
series of quadrats. In this method, the transect line is laid out across the
area to be surveyed and a quadrat is placed on the first marked point on
the line. The plants inside the quadrat are then identified and their
abundance estimated.
b) If possible, using a quadrat carry out random sampling of plant species on the school
playing field and complete the exercises below. Use LogIt sensors to measure at least
-3-
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
one physical factor which could be affecting plant distribution.
Results table:
PLANT NAME 1
2
3
4
5
6
7
8
grass
Biology workbook
9
10
MEAN
daisy
dandelion
buttercup
PHYSICAL
FACTOR
Bar chart
Draw a suitable bar chart of your mean results for each species:
Draw the bar chart in descending order of abundance, e.g. If
grass is the most common plant then draw its bar first. If buttercup
is the least common, draw its bar last.
Conclusion:
Describe and explain your results fully:
-4-
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
Biology workbook
Plants on the school playing field are adapted to withstand regular
mowing. Grass grows from the base of its leaves so cutting off the
tips will not damage the grass nor stop it from growing.
Other plants e.g. daisy, buttercup, plantain, dandelion, are all low
growing plants which grow horizontally more than vertically. This
means that their growing tips are below the blades of the mower,
so the plants are not killed and can continue growing after
mowing.
Evaluation:
What were the limitations of your technique and how might they be overcome?
Sample size – increasing sample size increases the RELIABILITY
of the results
Identification of plants – check with your teacher or use a good
identification guide or key to improve the ACCURACY of the
results.
Location of quadrats - ensuring the area is REPRESENTATIVE of
the whole playing field increases the RELIABILITY of the results.
c) If possible, using a transect carry out systematic sampling of plant species on the
school playing field and complete the exercises below. Use LogIt sensors to measure at
-5-
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
least one physical factor which could be affecting plant distribution.
Results table:
PLANT NAME 1
2
3
4
5
6
7
8
bare soil
grass
daisy
dandelion
buttercup
PHYSICAL
FACTOR
Present your mean results for each species in a suitable way:
Conclusion:
Describe and explain your results fully:
-6-
Biology workbook
9
10
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
Biology workbook
Hopefully there will be some CORRELATION between the
physical factor and the plants found, e.g. if the transect goes
under trees the plants found might change because not all will be
able to survive the reduced light intensity under the trees. The
plants will be outcompeted for light and possibly for water too.
Evaluation:
What were the limitations of your technique and how might they be overcome?
Sample size – increasing the number of transects (or using results
from other grouos) increases the RELIABILITY of the results
Identification of plants – check with your teacher or use a good
identification guide or key to improve the ACCURACY of the
results.
Location of transects - ensuring the area is REPRESENTATIVE of
the whole sample area increases the RELIABILITY of the results.
Additional Notes:
-7-
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
AQA Past paper question.
-8-
Biology workbook
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
Biology workbook
1 Red squirrels live in trees. They eat seeds from the cones of conifer trees. Squirrels
store cones in ‘larders’ on the ground. These larders provide food through the winter.
Each red squirrel makes and defends one larder.
Scientists monitor squirrel numbers to find the best habitats for the squirrel’s survival. In
one investigation, scientists estimated the numbers of squirrels in different types of
woodland. Each woodland contains a different species of conifer tree.
Here is their method.
Ten woods of each type of woodland were surveyed.
In each wood scientists measured out two transects (strips), each 600 m long and
10m wide.
A scientist walked slowly down the centre of each transect, recording the number of
squirrel larders he could see.
(a) (i) How many transects altogether did the scientists survey in each type of
woodland?
Number of transects .......................................
(1 mark)
(ii) What was the total area surveyed in one wood?
.
..................................................................................................................................
Area .................................. m2
(1 mark)
(b) Name one variable that was controlled in this investigation.
.........................................................................................................................
(1 mark)
(c) (i) The scientists recorded the number of larders instead of the number of squirrels
they saw.
Explain how this could have increased the accuracy of the investigation.
...................................................................................................................................
....................................................................................................................
(1 mark)
(ii) This method of counting the number of larders could have led to an inaccurate
estimate of the number of squirrels.
-9-
Wellsway school science dept.
Curriculum 2011 – AQA Additional Science
Biology workbook
Explain how.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
........................................................................................................................
(2 marks)
(d) The results of the investigation are shown in the graph.
The horizontal mark on each bar represents the mean number of larders per hectare of
woodland.
The range of the number of larders observed for Douglas fir woodland was 0 to 1.9 per
hectare.
(i) What was the range of the number of larders per hectare in the Spruce fir woodland?
.........................................................................................................................
(1 mark)
(ii) The highest mean number of larders per hectare was found in Blue spruce
woodland.
Suggest one explanation for this.
...................................................................................................................................
........................................................................................................................
(1 mark)
(H PAPER – JAN 2007)
- 10 -