Madania Secondary School
Grade 7 Biology Worksheet-Reinforcement
The Interdependence of Living
Organisms
Name: ________________________________
Class:
7 __ Date: __________
Answer these following questions correctly.
1. The figure shows a food web which includes some organisms in the African grasslands.
Oxpecker
bird
Scops Owl
Lion
Giraffe
Gazelle
Acacia tree
Elephant
shrew
Chameleon
Grasshopper
Click
beetle
Tick
Water
buffalo
Grass
a. (i) Draw a food chain consisting of four organisms. The organisms must be part of the food web.
(ii) Using examples from the food web, explain the difference between producers and
consumers.
b. When weather conditions are favorable the grasshopper population can suddenly increase
enormously. Predict and explain the effect this might have on the:
(i)
Scops owl population (ii) water buffalo
(iii) Giraffe population
2. This figure shows the carbon cycle diagram.
a. What do A, B, and C represent?
b. Which process is missing from the
diagram?
A
B
C
1112-S1-G07-BI-WS-REVIEW-DKS_111206
3. Deforestation occurs in many parts of the world.
a. Explain the effects deforestation can have on the carbon cycle.
b. Describe two effects deforestation can have on the soil.
4. Polar bears were listed as a threatened species under the Endangered Species Act in 2008.
(Taken from:
http://www.worldwildlife.org/who/media/press/2011/WWFPresitem
19837.html).
a. Suggest why polar bears are becoming a threatened species.
b. Describe methods of conserving threatened species such as
the polar bear or other endangered species.
5. Look at the nitrogen cycle diagram below.
a. What do X, Y, and Z represent?
b. What is the function of nitrogen fixing bacteria?
Protein in plants
death
Absorbed into plant
roots
detritus
Y
Nitrifying
bacteria
Decayed by Z
X
6. Population is a group of individuals of the same species living in the same habitat at the same time.
a. Explain what is meant by the term limiting factor as it applies to population growth.
b. List four limiting factors for population growth.
c. Take a look at this graph below. What facts that you may know based on the graph?
7. Some of the ways to increase the crop yields are the usage of pesticides and fertilizers.
a. Define the terms pesticide, insecticide, fungicide and herbicide.
1112-S1-G07-BI-WS-REVIEW-DKS_111206
b. Explain how pesticide can damage the environment.
c. Explain why farmers use fertilizers containing nitrate and phosphate on their fields?
d. Explain how fertilizer that was spread on a wheat field could have caused the death of fish in a
nearby pond.
8. Human activities are causing an increase in the concentration of greenhouse gases.
a. List the gases that contribute to the enhanced greenhouse effect.
b. Describe the consequences of global warming
c. Describe the ways in which people and their governments can reduce the emission of
greenhouse gases and attempt to reduce the effects of global warming.
9. Copy and complete the following sentences using the words below.
Acid rain
fossil fuels
nitric
nitrogen oxides
dioxide
sulfuric
When ___________________ containing sulfur are burned the pollutant gases, sulfur
_______________ and _________________are released into the atmosphere. These gases
dissolve in the rain to form _________________ acid and acid _________________.
10. Explain the meaning of each of the following:
a. Conservation
b. biodiversity
c. endangered species
11. Recycling means using materials again.
a. Make a list of materials that can be recycled.
b. Describe the main processes involved in the treatment of sewage and the recycling of safe
water.
1112-S1-G07-BI-WS-REVIEW-DKS_111206