Biology 12 past paper 2022

A man has hemophilia. Which statement correctly describes the inheritance?

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If an injury tore a small hole in the membrane surrounding the lungs, what effect on lung function is expected?

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How is a piece of DNA amplified through PCR? Explain the process in detail.

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Which tRNA can bind at mRNA codon **UAC**?

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What advantage does **uric acid** offer as a nitrogenous waste in arid environment?

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When a frog flips out its tongue to catch an insect flying past, it is showing which type of behavior?

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If blood pressure in the afferent arteriole leading to glomerulus decreased, how would the rate of blood filtration within Bowman's capsule be affected? Explain briefly.

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Describe techniques for the improvement of yield in crops and fruits.

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Why is an internal location of gas exchange tissue advantageous for terrestrial animals? List properties of respiratory surfaces.

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Explain the concept of **multiple alleles** giving **ABO blood group** as an example.

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When the pituitary gland releases growth hormone (GH), what is the effect on the liver?

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Which of the following structures produce the fluid protein of semen?

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Which of the following would increase the rate of heat exchange between an animal and its environment?

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Describe the basic pathway of information flow through neurons that causes one to turn one's head when someone calls their name.

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Describe how the process of gastrulation takes place in humans.

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What does the cat show when it runs for its food dish upon hearing the food can opener?

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Why is it nearly impossible to stop a reflex action from taking place? Write down the fundamental parts of a typical reflex arc.

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Albinism (lack of pigment) in man is caused by a recessive gene. If normal parents have an albino child, what is the probability that their next child be normal for color?

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Homeostasis of blood osmotic pressure is maintained by which organ(s):

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Critically analyze the inheritance of **hemophilia**, **colorblindness** and **muscular dystrophy**.

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Why are there so many variations of grain color in wheat? Explain.

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What type of heat exchange is promoted by **vasodilation**?

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What are the phenotypes and genotypes of parents of a colorblind son and non-carrier daughter?

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How are **joints** classified on the basis of their mobility? Write about any one common disorder of the skeleton.

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Emphysema is a condition that results in the destruction of alveoli in the lungs. What effect would this have on the body?

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What is **corpus luteum**? Briefly explain its role in menstrual cycle.

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Explain the process of repair of simple fracture of bone.

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What is **miscarriage**? What are the possible causes of miscarriage?

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Immediate source of energy for muscle contraction is:

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List some changes that occur at cellular level during aging.

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A trait whose alleles are present in both male and female but expresses more in one sex than other:

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Which types of cells have been proposed as **fourth germ layer**? What structures are derived from it?

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Reflex actions below the neck are under the control of:

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Why does the length of mRNA formed in eukaryotes shorten when it goes to the cytoplasm for translation? How is its message protected?

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Organisms of the same species inhabiting in space and time form a:

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Differentiate between: a. **Intron** and **exon** b. **Heterochromatin** and **Euchromatin** c. **Nucleosome** and **Primosome**

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Glands of male reproductive system in human are:

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How is atmospheric nitrogen fixed to be utilized by plants?

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The present giraffe has a long neck as compared to its ancestors. Lamarck believed it could be due to:

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Explain **genetic drift**. Write down its two causes.

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What is **succession**? How might the early species help the arrival of late species?

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Crumpled leaves like structure are found in $\dots$ stage of xerarch succession.

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If a forest near a lake is cut down, how will the quality of water be damaged? Also list non-conventional energy sources.

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What is the basic principle of Gel Electrophoresis? Write down its two applications.

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Myoglobin occurs in:

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What is cystic fibrosis? How is gene therapy used to cure it?

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Production of more individuals than the environment can support leads to:

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Write down three main steps involved in any DNA sequencing method.

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$Na^{+}-K^{+}$ ATPase pump is important for:

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What is meant by **tissue culture**? Write about two techniques used for animal cell culture.

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Which of the following is an environmental buffer?

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How are microbes utilized for energy production?

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Ovulation is stimulated by the sharp increase of which of the following hormones?

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Explain **integrated disease management**.

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A genome is a full set of genes in an:

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Explain $XO$-$XX$ type of sex determination with the help of an example.

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Specific sequences of four or six nucleotides arranged symmetrically in reverse order where restriction enzymes work are known as:

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Why is human male referred as heterogametic? Explain with the help of a cross.

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Study of proper utilization of economically important domesticated animal is known as:

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List the hormones of the anterior pituitary gland.

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During **PCR** which enzyme is used to do polymerization of DNA fragments?

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What are **hormones**? Give their classification on the basis of chemical nature.

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What is a **vaccine**? Give its importance.

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The pancreas releases which of the following hormones?

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What are **biological rhythms**? How are they important to man?

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The change of behavior by life experiences is called:

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Write three main causes of male infertility in humans.

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Which of the following cells are involved in soft callus formation during repair of bones?

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Write three causes of infertility in human females.

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Name the three germ layers. Which body organs are derived from these germ layers?

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What is **cleavage**? Write about two patterns of cleavage.

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Draw and label the water cycle.

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What is an ecological pyramid? Explain any two types.

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Describe the structure and function of voice box in humans.

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Write any three roles of microbes in human welfare.

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