Biology: Exam Fore

76. The ability of carnivores to survive in an ecosystem is dependent on the availability of prey. This can be considered as

A. abiotic factor.
B. catastrophic factor.
C. biotic factor.
D. edaphic factor.

77. The two reverse processes that play a significant role in absorbing and releasing carbon dioxide, respectively are

A. combustion and photosynthesis.
B. decomposition and respiration.
C. photosynthesis and respiration.
D. respiration and assimilation.

78. Which one of the following adaptations is important for survival of polar bear in very cold environments? Having

A. smaller size
B. blubbers under the skin
C. thick wrinkled ears
D. fine silky fur

79. This item is based on the following pyramid of biomass.

Which alternative contains organisms that can occupy the above pyramid of biomass from the bottom to the top?

A. Grass, Cricket, Chicken and Lizard
B. Grass, Cricket, Lizard and Chicken
C. Grass, Lizard, Cricket and Chicken
D. Grass, Chicken, Cricket and Lizard

80. A student concluded that the stage of meiosis on a prepared slide of plant tissue he observed was Anaphase II. What do you think was the reason to come to this conclusion? Observation of

A. divided centromere and separated sister chromatids
B. reformed nuclear envelope and reappearance of nucleolus
C. crossing over between non-sister chromatids of homologous pairs
D. one chromosome from each homologous pairs at the poles

81. Which one of the following properties of enzymes shows their catalytic nature?

A. Being non-specific to substrates
B. Reducing the activation energy
C. Changing the nature of the product
D. Being altered in a chemical reaction

82. Which one of the following minerals are used as cofactor for the enzyme alcohol dehydrogenase?

A. Cobalt ions
B. Magnesium ions
C. Zinc ions
D. Ferrous ions

83. If an enzyme is named as "EC 3.4.11.1" in a systematic naming, what does the number "3" represents? It represents the

A. sub-subclass of an enzyme in relation to its protein nature.
B. ultra-subclass of an enzyme that is related to the place where they act.
C. main class of an enzyme which indicates the type of reaction it catalyses.
D. sub-class of an enzyme in relation to the source from where it was discovered.

84. In the lock-and-key model of enzymatic action, the activation energy is lowered through

A. provision of alternative pathway for the reaction.
B. straining of the substrate molecules bound to the active site.
C. permanent modification of the active site of the enzyme.
D. conformational change of substrate molecules.

85. A student made an exprenent to observe the effect of temperature on catalase of mashed potato, After three parallel trials, he obtained the following results.

Temperature/°C	Time taken to collect 33 cm³ in seconds				Rate cm³/sec
Temperature/°C	Trial 1	Trial 2	Trial 3	Mean	Rate cm³/sec
10	54	47	43	48	0.69
20	12	14	16	14	2.36
30	5	5	5	5	6.6
45	14	11	11	12	2.75
50	73	71	57	67	0.5
55	119	109	132	120	0.27

At which temperature was the reaction fastest based on the following results?

A. 10°C
B. 30°C
C. 55°C
D. 50°C

86. Which one of the following plant species is endemic to Ethiopia?

A. Percica papaya
B. Aurocaria baramuleta
C. Guizotia abyssinica
D. Eucalyptus globulose

87. Which one of the following national parks of Ethiopia is declared as the world's heritage site and comprises endemic animals like Walia ibex?

A. Yangudi Rassa National Park
B. Simien Mountain National Park
C. Bale Mountain National Park
D. Rift Valley National Park

88. A mother milks her cow every morning and the milk usually forms curd after three days. What is the first step to investigate why this change happens?

A. Take action to prevent the milk from curdling
B. Read scientific articles about the reason for curdling of milk
C. Ask a question why the milk forms curd
D. Formulate hypothesis about the reason for milk curdling

89. A drug efficacy test was conducted under similar set up on two groups of infected mice (A and B), groups A were the control whereas group B were experimental group. A student gave a placebo to the control group and the drug to the experimental group. At the end, the experimental group got better. Which one of the following is true about the result?

A. Conclusion cannot be reached.
B. The drug has an effect.
C. Placebo has better effect.
D. The experiment was wrong.

90. Suppose you did an experiment in a biology laboratory and need to report your work to your biology teacher. Which one of the following steps is correct to report the finding?

A. Title → Procedure → Result → Hypothesis → Prediction → Evaluation → Conclusion → Acknowledgment
B. Title → Hypothesis → Procedure → Prediction → Conclusion → Result → Evaluation → Acknowledgment
C. Title → Hypothesis → Prediction → Procedure → Result → Conclusion → Evaluation → Acknowledgment
D. Title → Hypothesis → Prediction → Procedure → Result → Conclusion → Evaluation → Acknowledgment

91. Assume your friend has a blood type that has no antigen on his red blood cells but produces antibodies a and b, loses blood due to a car accident. If blood transfusion is necessary to save his life, your friend can receive blood from someone with

A. blood type AB.
B. blood type B.
C. blood type O.
D. blood type O.

92. The binomial system of naming developed by Linnaeus comprises two names. Which hierarchical groups are used?

A. Order and family
B. Kingdome and species
C. Genus and species
D. Genus and species

93. Which one of the following is the feature of kingdom Monera? Its members are

A. unicellular without separated nucleus.
B. multicellular with cell walls.
C. reproduced by hypha formation.
D. mainly autotrophic and saprophytic.

94. Which alternative given below is comprised of harmful groups from the kingdom Monera, Protista and Fungi, respectively?

A. Trypanosoma, Plasmodium falciparum and Haemophilus ducreyi
B. Candidaalbicans, Mycobacterium tuberculosis and Trypanosoma
C. Haemophilus ducreyi, Trypanosoma and Tinea pedis
D. Haemophilus ducreyi, Trypanosoma and Tinea pedis

95. Which one of the following is a feature of Octopi and squid in phylum mollusca? They have

A. segmented body with head and thorax.
B. well-developed brain
C. hard muscular foot with a hard body.
D. lung as a breathing structure.

96. Which one of the following organic molecules has ester bonds in its molecular structure?

A. Triglyceride
B. Glycogen
C. Cellulose
D. Amino acid

97. Which one of the following statement is correct about the structural organization of hemoglobin? It is formed

A. when a polypeptide chain folds itself during protein synthesis.
B. through the association of two or more polypeptide chains.
C. by hydrogen bonding between quaternary and tertiary structures.
D. through folding of secondary structure of a polypeptide chain.

98. The presence of large amount of lipid reduces the density of an animal. Which function of triglycerides is related to this fact?

A. Thermal insulation
B. Buoyancy
C. Respiratory substrate
D. Waterproofing

99. The missing number represented by the letter “n” in the formula of maltose (C₁₂H_nO₁₁) is

A. 12.
B. 11.
C. 22.
D. 24.

100. A student conducted a food test on three unknown food samples and obtained results as presented in the table below. What do you conclude from the result of the above experiment?

No	Procedures used	Colour changes of the food samples after the experiment
No	Procedures used	Food sample 1	Food sample 2	Food sample 3
1	Mixed with Benedict's reagent and heated	Blue	Red	Yellow
2	Mixed with ethanol and poured into water	Colourless	Colourless	Colourless
3	Mixed with Biuret's reagent	Mauve	Mauve	Mauve
4	Iodine solution	Brown	Brown	Brown

A. Lipids and reducing sugars are absent from all the three food samples tested.
B. Proteins and reducing sugars are found in all the food samples at equal concentrations.
C. Reducing sugars are found in two of the samples and proteins are found in all the samples.
D. Non - reducing sugars are present in all the food samples at different concentrations.

Biology Exam (Continuation): Questions 76 - 100

Exam Results