ASVAB Science Biology Practice Test 2

Question – 1

1. A mutation in the intrinsic factor gene leads to

  • A. Night blindness

  • B. Osteoporosis

  • C. Pernicious Anaemia

  • D. Pellagra

  • E. Diabetes insipidus

  • Answer:C

  • Answer Explanation:Intrinsic factor is needed for the absorption of vitamin B12. Vitamin B12 is needed for blood formation. So lack of functional intrinsic factor gene leads to pernicious anaemia.

Question – 2

2. Hormone secretin is secreted by

  • A. Posterior pituitary gland

  • B. Adrenal cortex

  • C. Stomach

  • D. Duodenum

  • E. Hypothalamus

  • Answer:D

  • Answer Explanation:Secretin is the hormone produced by mucosa of duodenum. It secretes pancreatic juice and inhibits gastrin secretion and thus regulates the secretions of pancreas and stomach. Secretin is secreted by duodenum in response to acidic food.

Question – 3

3. Which of the following genes code for an allosteric protein in lac operon?

  • A. Lac A

  • B. Regulator gene

  • C. Operator gene

  • D. Lac Z

  • E. Lac Y

  • Answer:B

  • Answer Explanation:Regulator gene codes for a repressor molecule which is referred to as an allosteric protein as it can have two slightly different shapes. In one form it binds to the operator gene and suppress its activity and in another form it is unable to bind to the operator gene, thus making operator gene active.

Question – 4

4. Which of the following microscopes are used to observe live unstained cells?

  • A. Bright field microscope

  • B. Scanning electron microscope

  • C. Transmission electron microscope

  • D. Phase contrast microscope

  • E. Both B and C

  • Answer:D

  • Answer Explanation:Phase contrast microscope uses differences of the phases of light transmitted or reflected by a specimen. It forms distinct, contrasting images of different parts of the specimen. Phase contrast microscope is used to observe living cells in its natural state without staining. It is used to study the ultra structure of cells.

Question – 5

5. Cleavage depends on

  • A. Axis of the egg

  • B. Position of nucleus

  • C. Amount of cytoplasm

  • D. Yolk content of the egg

  • E. Gaseous exchange

  • Answer:D

  • Answer Explanation:Cleavage depends on the yolk content of the egg. Depending on the yolk content, the cleavage can be holoblastic (total cleavage) or meroblastic (partial cleavage). Little yolk content leads to holoblastic cleavage. Higher yolk content leads to meroblastic cleavage.

Question – 6

6. Which of the following is not a correct statement regarding primary xylem?

  • A. Conducts mineral and water from root to stem

  • B. Conducts nutrients from leaves to other parts

  • C. Consists of vessels and tracheids

  • D. Consists of xylem fibres and xylem parenchyma

  • E. Protoxylem and metaxylem are its two types

  • Answer:B

  • Answer Explanation:The vascular system of plants mainly constitutes xylem and phloem. Xylem conducts water and minerals from root to stem and leaves. It has different elements such as vessels, tracheids, xylem fibres and xylem parenchyma. Protoxylem is the first formed element and the metaxylem is the later formed element of xylem. Phloem’s function is conducting nutrients from leaves to other parts of plant.

Question – 7

7. Hemimetabolous refers to

  • A. Incomplete metamorphosis of insects

  • B. Complete metamorphosis of insects

  • C. Adults of insects and nymphs that lack wings

  • D. An insect with chitin exoskeleton

  • E. A class of arthropods that lack larval stage during development

  • Answer:A

  • Answer Explanation:Hemimetabolous refers to incomplete metamorphosis of certain insects. The nymph often resembles the adult, as they have compound eyes,developed legs and wings. Pupal stage is absent in hemimetabolous stage. Complete metamorphosis of insects is called holometabolous. This includes pupal stage.

Question – 8

8. Haemagglutinin spikes are found on the surface of

  • A. Fungi

  • B. Cyanobacteria

  • C. Virus

  • D. Prions

  • E. Diatoms

  • Answer:C

  • Answer Explanation:Haemagglutinin spikes are virally coded integral membrane protein found on the surface of some viruses like influenza virus. They are needed for attachment of the virus to the target cell.

Question – 9

9. Feulgen stain is used to stain

  • A. DNA

  • B. RNA

  • C. Proteins

  • D. Lipids with saturated fatty acids

  • E. Lipids with unsaturated fatty acids

  • Answer:A

  • Answer Explanation:Feulgen stain, used to stain DNA, depends on acid hydrolysis of DNA. The stain was discovered by Robert Feulgen. The staining method can be used to identify the chromosome number.

Question – 10

10. An ant shares its food with its fellow member. This phenomenon is termed as

  • A. Altruism

  • B. Trophallaxis

  • C. Agonistic

  • D. Motivation

  • E. Taxis

  • Answer:B

  • Answer Explanation:Trophallaxis is a behavior seen in some social insects like ants, bees etc. It involves the direct transfer of food or other fluids among the family members. Mode of feeding can be either mouth to mouth (stomodeal) or anus to mouth (proctodeal). Trophallaxis also serves as a means of communication.

Question – 11

11. The stimulated sensory receptors pass the information to

  • A. Excretory system

  • B. Integumentary system

  • C. Endocrine system

  • D. Nervous system

  • E. Circulatory system

  • Answer:D

  • Answer Explanation:The human sensory system is a part of nervous system which is capable of responding to external stimuli such as sound, light, touch, smell etc. It consists of sensory receptors that are made up of neurons which transmit the stimuli in the form of nerve impulses to the central nervous system for response.

Question – 12

12. Which of the following statements is true?

  • A. Nucleoside contains of a six carbon sugar

  • B. Nucleoside is composed of nucleic acids

  • C. Nucleoside is composed of nucleotides

  • D. Nucleotide is composed of nucleic acids

  • E. Nucleic acid is composed of nucleotides

  • Answer:E

  • Answer Explanation:Nucleic acid is made up of many nucleotides. Nucleoside combines with a phosphate group to form nucleotide. A nucleoside is made up of a five carbon sugar and a nitrogenous base.

Question – 13

13. The enzyme involved in the synthesis of mRNA is

  • A. RNA polymerase I

  • B. RNA polymerase II

  • C. RNA polymerase III

  • D. Ribonuclease

  • E. Hexokinase

  • Answer:B

  • Answer Explanation:RNA polymerase II is involved in the synthesis of mRNA. RNA polymerase I and III are involved in synthesis of rRNA andtRNA respectively. Ribonuclease cleaves the RNA molecule. Hexokinase phosphorylates a hexose sugar.

Question – 14

14. Intron containing genes are called

  • A. Silent genes

  • B. Pseudogenes

  • C. Structural genes

  • D. Split genes

  • E. Gap genes

  • Answer:D

  • Answer Explanation:Split genes are composed of exonic sequences separated by introns. They are found only in eukaryotes. Genes that don’t have the capability to produce proteins are called pseudogenes. Gap genes are protein coding genes needed for the development of an organism.

Question – 15

15. In which stage of cell division are the primary oocytes arrested in humans?

  • A. Metaphase I of meiosis

  • B. Anaphase II of meiosis

  • C. Diakinesis

  • D. Diplotene

  • E. Pachytene

  • Answer:D

  • Answer Explanation:In humans, the oogonia divide from second to seventh month of gestation to form germ cells. Later they enter the meiotic stage to form primary oocytes. Primary oocytes are arrested at diplotene stage of prophase I and maintained up to puberty and resume meiosis during each periodic menstrual cycle.

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