2009

Life Science (Biology), Grades 3–5

• Characteristics of Plants and Animals• Structures and Functions• Adaptations of Living Things

• Energy and Living Things

Characteristics of Plants and Animals

1. Classify plants and animals according to the physical characteristics that they share.

Sort plant and animal pictures based on physical characteristics.

Use a dichotomous key to identify plants and animal.

Structures and Functions

2. Identify the structures in plants (leaves, roots, flowers, stem, bark, wood) that are responsible for

• food production• support• water transport• nutrient transport• reproduction• growth• protection

Observe-- plant/pollinator interaction seed dispersal methods.

Study maple trees and go maple sugaring. Identify the structures in the maple tree and their functions.

3. Recognize that plants and animals go through predictable life cycles that include

birth growthdevelopmentreproductiondeath.

Grow plants from seed. Document the complete life cycle of the plant.

Describe emergence of structures and the functions of these structures. Record changes in height over time. Graph the data.

• 4. Describe the major stages that characterize the life cycle of the frog and butterfly as they go through metamorphosis.

• Using either live organisms or pictures/models, observe the changes in form that occur during the life cycle of a butterfly or frog.

Adaptations of Living Things

5. Differentiate between observed • characteristics of plants and animals that are fully

inherited (e.g., color of flower, shape of leaves, color of eyes, number of appendages)

• characteristics that are affected by the climate or environment

(e.g., browning of leaves due to too much sun, language spoken).

• Make frequency tables of the number of students with certain inherited physical traits,

e.g., eye color, hair color, earlobe free or attached.

6. Give examples of how inherited characteristics may change over time as adaptations to changes in the environment that enable organisms to survive

e.g., shape of beak or feet, placement of eyes on head, length of neck, shape of teeth, color.

• Compare and contrast the physical characteristics of plants or animals from widely different environments (e.g., desert vs. tropical plants

aquatic vs. terrestrial animals). • Explore how each is adapted to its environment.

7. Give examples of how changes in the environment (drought, cold) have caused some plants and animals to die or move to new locations (migration).

• Investigate how invasive species out-compete native plants (e.g., phragmites and purple loosestrife).

• Discuss how some native plants die as a result.

8. Describe how organisms meet some of their needs in an environment by using behaviors (patterns of activities) in response to information (stimuli) received from the environment.

*Recognize that some animal behaviors are instinctive (e.g., turtles burying their eggs), and others are learned (e.g., humans building fires for warmth, chimpanzees learning how to use tools).

Discuss how newly born sea turtles find their way to the ocean. Discuss how pets are trained to learn new tricks. Discuss how migrating birds navigate. Discuss the actions that coastal species take to adjust to the changing

levels of the tide. Observe an earthworm placed on top of soil in a container that is

exposed to light. Discuss how its ability to sense light helps it survive (by burrowing)

and how its structure allows it to burrow through soil.

9. Recognize plant behaviors, such as the way seedlings’ stems grow toward light and their roots grow downward in response to gravity.

*Recognize that many plants and animals can survive harsh environments because of seasonal behaviors, e.g., in winter, some trees shed leaves, some animals hibernate, and other animals migrate.

• Set a germinating bean in a glass filled with water next to an asymmetric source of light.

• Allow the root and stem to grow a few inches. Rotate the bean so that the roots are now touching the water at an angle and the stem is away from the light source. Observe how the root system and stem respond to this change by changing their direction of growth

10. Give examples of how organisms can cause changes in their environment to ensure survival.

*Explain how some of these changes may affect the ecosystem.

Discuss the importance of wetlands to human survival. Investigate how an invasive species changes an ecosyste

m. Research local projects where humans are changing the e

nvironment to ensure a species’ survival.

Energy and Living Things

11.Describe how energy derived from the sun is used by plants to produce sugars (photosynthesis) and is transferred within a food chain from producers (plants) to consumers to decomposers.

• Make a food chain. Begin with the sun as the source of energy and end with decomposers. Create links that show the relationships of plants and animals in the chain.

• Show the direction of the flow of energy. • Discuss results if various links in the chain are broken.

• The four pictures below show how a pond environment changed from 1900 to 2000.Which of the following processes was most directly responsible for the changes that occurred in the pond environment?

» A. freezing» B. evaporation» C. sediment deposition» D. chemical weathering

• Which of the following best describes a role of mushrooms in ecosystems?

• A. capturing energy from sunlight

• B. consuming living plant material

• C. service as food for human

• D. breaking down dead plant material

• Which of the following statement is not true for H1N1 virus?

• (A) It is composed of cells

• (B) It is able to infect swine

• (C) It is a new strain of Influenza virus

• (D) It has been reported of sever pneumonia cases on infected patient.

• List three ways to reduce the spread of influenza infection

• Population growth pattern of bacteria is very important in a fermentation industry. If an Erlenmeyer flask containing nutrient broth was inoculated by a certain amount of bacterial cells (No) at To, after a certain period of time the bacteria will show a specific growth curve.

• In the beginning of growth (To – T1) the cells are under adaptation phase.

• After adaptation phase, cells start to multiply by binary fission process. Each cell will divide, and become two cells.

• In a closed system where the nutrient supply is limited, the population of dividing cells will become relatively the same amount with the dead cells (T2 – T3).

• After T3 the amount of dead cells will be higher than the living ones, then eventually all cells will die.

•

The growth curve (N in logarithmic scale) from the above description is:

• The plant structures (the sketch is not the real size).

• Fill in a box for appropriate plant’s organs of:

• 1. Monocots :

• 2.Dicots :

A. Heat EnergyB. Light EnergyC. Chemical EnergyD. Chemical cycling

The picture below shows a terrarium ecosystem, with four (4) processes occurring in it which are symbolized by I to IV.From the picture, process II involves :

I

II

IIIIV

• Every organism consists of cells.• 1. Select correct group of organisms listed in the

Table 2 below and match it with Figure 2a and 2b

• Avian Influenza or ‘bird flu’ is a contagious disease of animal caused by viruses that normally infect only bird and less commonly pigs. Avian Influenza viruses are highly species-specific, but have, on rare occasion, crossed the species barrier to infect humans.

• Avian Influenza viruses have 16 H (H1 – H16) subtypes x 9 N (N1 – N9) subtypes. Among them are known to cause highly pathogenic form of the diseases. However, not all the subtypes of the viruses are highly pathogenic and not all will cause severe disease in poultry.

• 1. Based on current understanding, viruses are introduced to poultry flock in their low pathogenic form. Allowing them to circulate in poultry population within few months, usually the viruses undergo mutation into a highly pathogenic form. The virus subtype that we (human) are most concerned about, are: ……., and ……..

• 2 .Is the virus transmitted easily from birds to humans ? • A. Yes, avian influenza virus is easily transmitted to

human, especially in chicken farms area• B. Yes, avian influenza virus can be transmitted from

chickens/bird to human, because human and chickens/bird posses the same virus receptor

• C. No, because human does not have the particular virus receptor

• D. No, because only relatively small number of people is infected compared to the significant number of infected chickens and birds

• 15. In general, plants have a much larger surface area/volume ratio. What is the main reason for this?

• (A) The advantages of having a larger body surface in plants are correlated to the area of light absorption.

• (B) Plants, in general, are bigger than animals. • (C) Animals need a larger volume in order to

store water. • (D) Animals have more complex chemical

substances in their bodies.

• 16. The organic pesticides were developed in the 1940s. Their effectiveness against crop diseases surprised everybody at the time. On the other hand, their high persistence in the environment resulted, after a period of time, in a large incidence of mortality of birds, which didn't come into direct contact with these products. This fact is related to the ecological concept of trophic magnification which means:

• (A) Degeneration of the food chain. • (B) Accumulation of toxic residues in the large anima

ls, because those consume larger quantities of food. • (C) Gradual increase in the concentration of the toxic

products at every trophic stage in the food chain. • (D) A larger resistance of the animals of lower trophi

c levels to the toxicity of those products in relation to animals in upper trophic levels.

• 17.Water plays an important role in biology. Indicate the option that presents the correct affirmative about this liquid.

• (A) The metabolic activity of a cell is directly related to its hydration condition.

• (B) Water living beings obtain oxygen needed for their respiration from water molecules.

• (C) The terrestrial living beings do not depend on water for their reproduction, respiration and metabolism.

• (D) Water dissolves only cellular molecules, but does not participate in the cellular metabolic activities.

• 18. The majority of the energy used in the planet today is produced by burning fossil fuels. The Kyoto protocol, an international agreement that includes the decrease in the emission of CO2 and other gases, demonstrate the present preoccupation with the environment. The excess of fossil fuel burning can have as consequences:

• (A) Increase in acid rains and increase in the ozone layer.

• (B) Increase in the greenhouse effect and the level of the oceans.

• (C) Global temperature decrease and increase in the levels of oceans.

• (D) Destruction of the ozone layer and decrease of the greenhouse effect.

• 19. One of the problems in the use of solar energy as an alternative energy source is the difficulty in storing that energy. Some group of living beings developed the capacity of storing that energy in organic compounds to use in their metabolic processes.

• The process of storing this energy and example of groups that can perform it are, respectively:

• The figure shown below is the food-network of a community. Which one of the following consumers, if it becomes extinct, will make the most significant impact on this ecosystem?

(A) Lizards (B) Snakes (C) Eagles (D) Rats

• For several years, Mr. Tu had continuously been applying a certain amount of X-pesticide on the field for reducing the damage of pests on rice production. For each year, he counted pests found in the rice field by numbers/m2 and plotted the results shown in Figure

• According to the above observation, Mr. Tu concluded that the X-pesticide was very effective in the earlier years, but, it gradually became ineffective in later years. Based on the above information, please answer the following questions.

• III-3-A

• By examining the data shown in Fig., which year was the first year for applying X-pesticide?

• III-3-B• Which one of the following statements matches Mr. Tu’s

conclusion? • (a) Mutations happened in Mr. Tu’s rice plants and the m

utated rice plants attracted a large quantity of various other pests to come.

• (b) A pesticide-resistant line was developed in the pest population, after which the number of the pesticide-resistant insects increased.

• (c) Bad quality control in the production of the pesticide resulted in the ineffectiveness of the pesticide.

• (d) After Mr. Wang applied X-pesticide in the field, heavy rains reduced the efficiency of the pesticide.

• III-3-C• Based on the study of Mr. Tu, to prolong the effe

ctiveness of X-pesticide, which one of the following suggestions is the best?

• (a) Lowering the applied dosage of X-pesticide every year

• (b) Doubling the applied dosage of X-pesticide every year

• (c) Alternation of high and low X-pesticide dosages on a yearly basis

• (d) Alternating application of X-pesticide with another effective pesticide each year.

ANS• III-3 Pests in the rice field• III-3-A (0.4 point) • By examining the data shown in Fig.III-3, which year was the first ye

ar for applying X-pesticide?• Answer: 2003. The number of pests in 2003 was smallest.• III-3-B (0.3 point) • Which one of the following statements matches Ms. Tu’s conclusion?• Answer: (b).• III-3-C (0.3 point) • Based on the study of Ms. Tu, to prolong effectiveness of X-pesticid

e, which of the following suggestions is the best?• Answer: (d) • Alternating application of X-pesticide with another pesticide ea

ch year could decrease the formation of pesticide-resistant lines.

• A25. The diagram below shows a typical foodweb of a rice paddy.• Regarding this foodweb, which of the following statements are true?• (a) Biomass decreases as you go up the trophic level in this foodwe

b. • (b) Heron has the most impact on this ecosystem.• (c) If the number of spiders decreases, the number of brown plantho

ppers will increase. • (d) If the number of heron increases, the amount of rice will increase.

• (e) If the number of grasshoppers increases, the amount of rice will

decrease.

• (A)a, e (B) b, d (C) a, c, d (D) b, c, e

• 26. The graph below shows experimental results which regards hatching of fruitfly eggs. A researcher hatched fertilized eggs at 10 , 15 , ℃ ℃20 , 30 after they were incubated at 2 (E℃ ℃ ℃xp. I) or at 21 (Exp. II) for 3 days.℃

• Select an option with the optimum incubation temperature and optimum hatching temperature.

• 18. Biological species concept is stressed on the organism’s ability to interbreed and produce viable and fertile offspring. Different species are separated by barriers that prohibit interbreeding; it also called as reproductive isolation.

• Which of the following isolating mechanism is responsible for the origin of the Darwin finches on Galapagos island?

• A. Geographical isolation• B. Mechanical isolation• C. Behavioral isolation• D. Temporal isolation

• 19. The information of the physical world outside our body, as well as the processes inside, is collected by sensory receptors. Most of these receptors are specialized neurons or epithelial cells, existing in single or groups with other types of cells within the sensory organs. Choose the correct match among organs, sensory cells and receptor types from the table below.

A. I, 1, bB. II, 2, cC. III, 3, aD. IV, 4, d

• A21. The foods that enter our digestive system will undergo several processes, which are function- and place-specifics. Choose the correct statement.

• A. While in the mouth, starch is broken down into disaccharide by the action of salivary amylase

• B. Stomach lining produces peptides• C. The function of large intestine is to produce digestive

enzymes• D. The function of small intestine is to absorb water

• C22. Global warming is considered as a big environmental issue. This phenomenon creates climate change, which causes several effects of different magnitudes.

• Minimum effect(s) of climate change can be observed on:• I. plant growth• II. plant flowering• III. deciduous trees losing leaves in the fall or dry season• A. I only• B. II only• C. II and III• D. I and III

• C23. AIDS (Acquired Immune Deficiency Syndrome) is caused by HIV (Human Immunodeficiency Virus). People with AIDS are susceptible to opportunistic diseases, infections and cancers that take advantage of the collapsed immune system. HIV suppresses the immunes system by killing the victim’s

• A. B-cells• B. Macrophage• C. T-cells• D. Plasma cells

• A24. Insects can provide important evidence in a crime investigation. Size and age of particular larvae found in corpse can be used to estimate the time of death. Which insects with larvae usually arrive earliest on human dead bodies?

• A. Blowflies• B. Ants• C. Mites• D. Dung beetles

• C23. The table shown below is the analytical data of mitochondrial DNA of four different, but related animal species.

• If you made a phylogenic tree of these four animals with the data above, which would be the correct answer? (You should consider the fewest change of sequence of bases in DNA)

• Episcia reproduces young plants by runners • From the picture above:• a. How many runners shown in the picture?• Answer: ___________________.

– Which one is the oldest runner?

• Answer: ___________________.– A runner is a special kind of ____________________.

• (choose one right answer: Stem/root/leaf/flower/plants)

*Part of plant which absorb water and mineral is __________.

*Part of plant which produces carbohydrates is ___________.

*Where is the food stored? ___________________________.

Which part of flower that function to attract the insect?

The flower indicates as : A)perfect flowerB)imperfect flowerC)complete flowerD)incomplete flower

• What is the name of the process which is responsible for the production of oxygen by green plants?

• Which statement about sexual reproduction in flowering plants is correct? – A)It is conducted through bud formation.– B)It requires the presence of petals.– C)It can be accomplished by grafting.– D)It gives rise to genetically diverse offspring.– E)It cannot result from self-pollination.

• Pollination in the flowering plants ________ .– A)never requires external water– B)never occurs within a single flower– C)always requires help by animal pollinators– D)is also called fertilization– E)make most angiosperms independent of ext

ernal water for reproduction

• Stomata in the typical green leaves, _______ .• A)are covered by a waxy cuticle• B)control the opening of guard cells• C)close when water is being lost at too great a r

ate• D)are usually most abundant on the upper epide

rmis of a leaf• E)release less water to the environment than oth

er parts of the epidermis

• Tuti conducted the experiment concerning the relationship between transpiration and leaf area in two different plants (plant A and plant B). She wrote the result of the experiment in a form of graph shown below.

0

2

4

6

8

10

12

14

0 2 4 6 8 10

leaf area (cm2)

tra

ns

pir

ati

on

ra

tes

(m

l/m

in)

• From the graph above:

• A. Explain how leaf’s area influences the transpiration of plant A and plant B.

• B. Which plant respirates faster?

The figure above show plant ringed in part 3.

Do branch 1 and 2 will still alive? Give reason to your answer!

Does branch 4 still can get photosynthesis product from leaves in branch 1, 2? Give explanation to your answer.

Donny conducts the experiment in the laboratory. He grows corn plants in two different environments. He sets up the plant A in an environment with low CO2 and plant B in a high CO2. He writes the result of his experiment as shown in a table below.

• A. Change the table above into a graph. Time on the horizontal axis and growth rates in the vertical axis

• B. How does carbon dioxide influence growth of the corn plants?

• C. Which plants has a higher growth rate?

• Look at the drawings 1 to 5 of the larvae of common freshwater insects (the drawing is not drawn to scale):

Identify each one in turn by using the key.No legs ……………………………………… go to no. 2Three pairs of legs present ………………. go to no. 3Bristles on all segments …………………..… CulexBristles not present on all segment ………… SimuliumOne tail fillament …………………………… SialisTwo tail fillament present ………………..… go to no 4Long fillament on head …………………….. PerlaShort fillament on head ……………….….…. Dyctisus

• From the table above answer these following questions:

• A)Which food is the richest protein?• B)Which food is a highest value in bone formatio

n• C)Which food would you recommend for someo

ne suffering from aptha/mouth ulcer?• D)How many calories would you obtain if you ate

a cheese sandwich containing 100 g of bread, 50 g of cheese and 2,5 g of butter?

Write down 2 plant’s parts that have function as storage organs!

If some of the leaves are eaten by caterpillar, is the plant still produce storage organs? Give the reasons!

Explain the stomata’s behavior in plant A and B based on the graph above!

Give the reason why some plants open the stomata during the night, while it must be closed during the day?

• Plants lose water through their leaves by transpiration. The graph below is the result of transpiration experiment using Hibiscus rosa-sinensis. Answer the questions based on the graph!

• When did the plant lose the most water and how much water evaporate from the plant?

• Answer:

• How do the plant lose the water? • Answer:

• When did the plant lose the least water? Why? • Answer:

• How can you explain these results? • Answer:

Part of the seed which stores food is _____________________

Part of the seed which grows into shoot is __________________

• According to the picture below, some plants trap and digest insect to fulfill their needs that is not available in soil. This ability is a kind of plant adaptation to the terrestrial ecosystem, which lacks …………….

• A)oxygen • B)hydrogen • C)nitrogen• D)sulphur • E)carbon dioxide

Look at the picture below. Acid rain may occur in this area due to the gases produced from human activities. The gases may react with water and form an acid. Which one of the following gases causes acid rain?

A)Nitric oxideB)oxygenC)carbon dioxideD)NitrogenE)Hydrogen

• Plant loses water through the leaves by transpiration. An experiment was set up to measure the loss of water from the leaves. Prior to the experiment, pot and soil were covered using the plastic bag, as shown in the picture. Loss of water from plant could be regularly measured by weighing the potted plant.

• When does the plant lose the most amount of water during the day?

– A)At noon. It is due to the highest temperature and maximum light intensity of the sun.

– B)At noon. It is due to the highest temperature and humidity at that time.

– C)At noon. It is due to the highest humidity and maximum light intensity of the sun.

– D)In the morning. It is due to the lowest temperature and humidity

– E)In the morning. It is due to the sun and temperature start to rise

• Why must the plastic bag cover the pot and soil?

• What will happen if all the leaf surfaces were covered by clear plastic? – A)The plant will die due to the lack of oxygen needed

for their respiration.– B)The transpiration will be disturbed due to the declin

e of pores needed for gas exchange. – C)The plant will die because less water enters the pla

nt. – D)The photosynthesis will be affected because the cle

ar plastic will prevent the sunlight from reaching the leaves

– E)The plant will die because the accumulation of carbon dioxide in leaves is toxic for plant.

Which one of the following statements indicates the correct food chain?

• Which one of the following statements indicates the correct food chain?

• A)1,2,3,4,5,6,7,8,9,10,11,12

• B)3,4,5,6,7,8,9,10

• C)5,6,7,8,9,10,11,12

• D)1,5,9,12

• E)1,2,3,4

• Overuse of pesticide can cause some of the following events:• 1.The plants die• 2.Most of the targeted pests die• 3.Soil organisms die• 4.Plants may grow rapidly• 5.Pests become resistant to pesticide • 6.Soil microorganisms grow rapidly

• Which of the following sets of statements is true?• A)1,2,3,4,5,6• B)1,2,3,4,5• C)1,3,5• D)2,4,5• E)3,6

1. Identify the part labeled “i” and state its function.

2. Identify the part labeled “f” and state its function.

• Some animals have strategies to escape from predators or enemies, such as producing a bad smell, changing color, etc. Which is the following tactics that is used by squid?

• A. By curling its body• B. By having an electric tail• C. By detaching its tail easily• D. By excreting ink• E. By changing body color

• Snakes are different from worms because snakes have .......

• A. Slime

• B. Eggs

• C. Segments

• D. Scales

• E. Color

• Which one of the activities described in the table below does not match the characteristic of all living things.

• Elvira wants to prove that plants need some nutrients in the soil. In order to test her idea she uses two pots of plant. She sets up one pot of plant as shown below.

• Which one of the following should she use as a control set-up?

• Choose a hypothetical graph to show the respiration of an animal in a closed chamber over a period of time.

Based on your understanding in biology, identify how many population in A and how many population in B.

• Desert is an area characterized by low rainfall, high evaporation and low humidity. In such a condition, desert plants survive by adapting themselves structurally and physiologically. Which of the following is the least possible adaptation of desert plants?– A. shallow and spreading roots– B. fleshy leaves– C. thin & wide leaves– D. green stems– E. thick-cuticle leaf

• Explain your answer.

• Two identical plants are grown in two different places, dark (plant A) and light (plant B).After some weeks, what is the appearance of both plants?

• Tofu (soybean curd) contains high amount of protein from soybean. Choose other examples

• of food which contains high protein:– A. Cheese– B. Bread– C. Potato chips– D. Chicken curry– E. Jelly

• Plants use water for …….• (1) cell growth ; (2) photosynthesis; (3)

germination• A. (1) and (2)• B. (1) and (3)• C. (2) and (3)• D. (1), (2) and (3)• E. None of them

• Animals in the house may indicate a potential disease that may be spread in the family. If you have a cat in the house, choose the following disease that may be spread by the cat to human:

• A. Dengue• B. Avian influenza• C. AIDS• D. Polio• E. Tuberculosis

• Why does the seed of the coffee have a very tough seed coat? The seed can ……….

• A. be dispersed by propulsion• B. extend the distance of its dispersal by

traveling breezes• C. adhere to passing animals• D. survive the mechanical forces and conditions

of the animal’s gut• E. attract the animals

• Which of the following statements about an animal’s size and shape is not true?

• A. larger animals require more food than smaller animals• B. larger animals produce more waste than smaller

animals• C. larger animals are more vulnerable to cold than

smaller animals• D. larger animals require more oxygen than smaller

animals• E. larger animals require larger area than smaller

animals

• If you want to make your plant increase in height, which part of the plant you have to cut?

• Choose the correct picture showing the path of light entering a normal eye?

• Which of the following substances can be recycled in an ecosystem?

• (1) carbohydrate; (2) water; (3) nitrate• A. (1) and (2)• B. (1) and (3)• C. (2) and (3)• D. (1), (2) and (3)• E. None of them

• In order to increase speed and agility, an animal uses different kinds of strategy. Complete the table by writing the body part used by the animal.

• Which of the following type of reproduction produces offspring with identical genotypes?

• (1) buds from the same potato tuber ; (2) seeds from the same tomato ; (3) spores from the same fungus.

• A. (1) and (2)• B. (1) and (3)• C. (2) and (3)• D. (1), (2) and (3)• E. None of them

• The following picture is a diagrammatic figure of various kinds of systems in animal.

………………..(4.1) pumps the blood to the lungs through ……… (4.2).Within the lungs, blood cells discharge carbon dioxide and take in oxygen.Oxygen-rich blood from the lungs goes back to the heart through ………(4.3), then it is pumped from the ……… (4.4) to all over the body through the ………(4.5).

• The following is a list of substances which can be found in blood. Match the substances with the correct description on the left box by putting only one letter in the blank box:

What are the conditions of the heart valves when the ventricles are all relaxed?A. Valves 1 and 2 are closed; valves 3 and 4 are open.B. Valves 1 and 3 are closed; valves 2 and 4 are open.C. Valves 1 and 3 are open; valves 2 and 4 are closed.D. Valves 1 and 2 are open; valves 3 and 4 are closed.E. All of the valves are open

• Some people may have a hole in the septum that separates chambers X and Y. What problem will they have?

• a. They may develop anemia.• b. They may have a lower blood pressure.• c. Their blood may not be able to clot normally.• d. Their arterial blood may not be fully

oxygenated• e. They may have a higher blood pressure

When there is a large defect between the atria, a large amount of oxygen-rich (red)blood leaks from the heart's left side back to the right side. Then this blood ispumped back to the lungs, despite already having been refreshed with oxygen. Thisis inefficient, because already-oxygenated blood displaces blood that needsoxygen. Many people with this defect have few, if any, symptoms.

• An ecologist studied the number of organisms in grassland area over a three year period:

• Pick from the following choices to answer question (a), (b), and (c):

• A. Mice population is increasing• B. Mice population does not depend on the area of grassland• C. Insectivorous birds is migrating into the area• D. The grassland area is decreasing• E. Insectivorous bird depends on population of grasshopper• F. The grassland area affects the population of bird

• (a) What is the best explanation for the decrease in the population of grasshoppers

• from year 1 to year 3? …..• (b) What is the best explanation for the change in the mice

population? ..• (c) What is the best explanation for the change in the bird

population?