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ScienceSaurus Reading Questions KEY
Read pages 129 – 137 to answer the following questions:
1. Ecosystem:
All the organisms that live in an area together with the nonliving factors of the environment.
2. Ecology:
The study of how organisms interact with each other and the physical environment.
3. Species:
A group of organisms that can mate and produce offspring that in turn can produce more offspring.
List 3 examples of species:
Dogs, Humans, Cows, Roses, Oak Trees, Other ideas?
4. Population:
All the organisms of the a species that live in the same place at the same time.
5. Community:
Multiple populations of organisms in a specific area (a community of pine trees, deer, mice, raccoons, bacteria,
mushrooms and ferns in a forest).
6. List 4 living factors (biotic) in the pine forest ecosystem picture on p. 130
Owl, deer, pine tree, fern, turtle, mushroom, raccoon, bacteria, mouse, frog.
7. List 3 non-living factors (abiotic) in the pine forest ecosystem picture on p. 130
Air, water, rocks.
8. Define limiting factors:
Things in the environment that limit how many organisms can live there.
9. List 4 limiting factors:
Food, water, light, living space.
10. Define niche:
The unique role an organisms plays in its habitat. Its job!
11. What is the difference between niche and habitat?
A habitat is an organism’s home or living space. Two organisms may share the same habitat, but no two
organisms can have the exact same niche.
12. How can deer, rabbits and squirrels share the same habitat but not compete for food?
They all have a different niche. Deer eat leaves higher up in the trees, rabbits graze on the grasses, and squirrels
eat acorns.
13. What the three main relationships between populations?
Competition, Predation, symbiosis.
14. Define competition:
When more than one organism or population competes for a limited resource (food, water or shelter).
15. What is the benefit of predator-prey relationships?
They help control population size, preventing any one population from getting too large and using up all of the
resources.
16. What do you think would happen if the predator relationship got too high?
One population may get so large that they use up the resources and take over the ecosystem. There would not be
enough resources for other organisms to live there.
17. What is symbiosis? A close relationship between two species.
Define
Mutualism
A relationship in which both species benefit
Examples: The tiny blackbird plover acts as a toothpick for the fierce crocodile and helps by removing tiny
morsels of food that is stuck between the crocodile's teeth. These food particles are the source of food for the
bird.
Another example is between the ostrich and the zebra. The ostrich always moves with the herd of zebras since it
has a poor sense of hearing and smell, whereas the zebra has very sharp senses. The ostrich has a keen sense of
sight, which the zebra lacks. Hence, these two species depend on each other to warn one another of any nearby
lurking dangers.
Some other examples of symbiotic relationships between two or more species are the bumble bee and the
flowering plants, the lichen (algae and fungus), human beings and the intestinal bacteria, the sea anemone and
clownfish, etc.
Commensalism
A relationship in which one species benefits and the other seems to be unaffected
Examples: Cattle egrets are mostly found in meadows and grasslands are always seen near cattle, horses and
other livestock. These birds feed on the insects that come out of the field due to the movement of the animals.
They even eat ticks, fleas, etc. off the back of animals.
The relationship between tigers and golden jackals is also commensalism. The jackal alerts the tiger to a kill and
feeds on the remains of the prey left by the tiger.
Parasitism
One organism feeds on the cells, tissues or fluids of another organism
One classic example of parasitism is seen in the case of intestinal parasites and humans, where the parasites
suck all the nutrients from the host's body but cause a series of ailments to the host.
Humans and lice are another example of parasitism.
Ticks, and fleas can also be found on animals as parasites. Plants get parasites too.
19. Define:
Decomposer
Producer
Organism that feed on the remains or waste of other organisms and recycle their nutrients
back to the environment.
Organisms that make their own food.
Consumer
An organism that gets its food by eating other organisms.
Carnivore
Meat-eaters, they get food by eating herbivores or other carnivores.
Scavenger
Eat the remains or organisms left behind by other animals.
Omnivore
Feed on both producers and consumers (plants and animals). We are omnivores.
20. Draw a food chain showing the connection between the following: Nile perch, humans, cichlids, algae, sun
(be sure to draw the food chain in the correct order). Identify the source of energy, primary consumer,
secondary consumer, tertiary consumer and producer in the diagram
Sun 
(Energy)
Algae 
(Producer)
Cichlids

Nile Perch

Humans
(Primary Consumer) (Secondary Consumer) (Tertiary Consumer)
21. What is the difference between a food chain and a food web?
A food chain traces the path of energy as it moves from one organism to the next in an ecosystem. A food web
is a system of several food chains that overlap. It gives a more complete picture of how organisms interact to
get food and shows how energy flows in an ecosystem.
22. Use the diagram on p. 135 to answer the following questions:
When the organisms die, their energy goes to bacteria and fungi which are called decomposers.
List 3 primary consumers: Cichlids, water flea, snail
The energy in this food web actually started with the Sun - it is how the pondweed gets its energy.
The pondweed uses the solar energy and converts it to chemical (food) energy.
List 3 tertiary consumers: Frog, Garter snake, Perch
How does the frog get energy? The frog eats the dragonfly
Which species get energy from the minnow? The perch, garter snake and the frog
Read pages 136-137 to answer the following questions:
23. How is energy lost in an ecosystem?
As organisms use energy to carry out life processes, some energy is lost as heat.
24. How much energy is passed from one level to the next? 10%
25. What is an energy pyramid?
An energy pyramid shows the decrease in energy at each level of the food chain, from producer to primary
consumer, to secondary and tertiary consumers.
26. Draw an energy pyramid for: algae, minnow, perch, human
Human
Perch
Minnow
Algae