All Free Biology MCQs with Answers
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19844 questions · page 698 of 1985
6971. Histones have an abundance of which amino acids?
- A. Alanine and glycine
- B. Tyrosine and cysteine
- C. Arginine and lysine
- D. Histidine and serine
Explanation: Histones are rich in basic amino acids (lysine & arginine), binding tightly to negatively charged DNA.
Correct answer: Arginine and lysine6972. There are _ chromosomes in a mosquito:
- A. 6
- B. 14
- C. 8
- D. 16
Explanation: The mosquito genome has 3 pairs (6 total) chromosomes.
Correct answer: 66973. Chromosomes were first observed by Walther Fleming in rapidly dividing cells of the _:
- A. Sea urchin
- B. Drosophila
- C. Salamander
- D. Penicillium
Explanation: Walther Flemming, a German embryologist, was the first person to systematically observe and describe the behaviour of chromosomes during cell division (mitosis) in the early 1880s. He used newly developed aniline dyes to stain cells of salamander larvae embryos, which allowed him to visualise minute, thread-like structures within the nuclei.
Correct answer: Salamander6974. Histones are linked to:
- A. Nitrogenous base of DNA
- B. Phosphate of DNA
- C. Sugar of DNA
- D. All of these
Explanation: Histones (positively charged proteins) bind with the negatively charged phosphate groups of DNA backbone, helping in packaging DNA into chromatin.
Correct answer: Phosphate of DNA6975. Statements: I. More than two billion pounds of chemicals are spewed in the air everyday by industries and vehicles of some countries II. International pollution control organisation is expected to penalise the countries which cross the maximum emission limits.
- A. Statement I is the cause and statement II is its effect
- B. Statement II is the cause and statement I is its effect
- C. Both Statement I and II are independent causes
- D. Both Statement I and II are effects of independent causes.
Explanation: The massive scale of pollution (Statement I) is the problem or cause. The expected penalty from a control organization (Statement II) is the logical consequence or effect aimed at addressing this problem.
Correct answer: Statement I is the cause and statement II is its effect6976. Statement: Most of those who study in premier engineering colleges in Pakistan migrate to developed nations for better prospects. Courses of Action:I. All students joining these colleges should be asked to sign a bond to remain in Pakistan for at least ten years after they complete their education.II. All those students who desire to settle in developed nations should be asked to pay the entire cost of their education which the government subsidizes.
- A. Only I follows
- B. Only II follows
- C. Either I or II follows
- D. Neither I nor II follows
Explanation: The statement highlights that many engineering graduates leave Pakistan for better opportunities. Course of action I is impractical and unethical, as it restricts personal freedom without addressing the real reasons for migration. Course of action II is also flawed, as subsidies are meant to develop national talent, not penalize choices.
Correct answer: Neither I nor II follows6977. MICROCOPY In a typical compound microscope, the resolving power is which is about: that of naked eye, respectively.
- A. 1.O mm. 250X
- B. 2.0 mm. 250X
- C. 2.0 um, 500X
- D. 1.O um, 500X
Explanation: Resolution of the human eye is 1.0mm. Resolution of compound microscope is 2.0um that is 500X of human eye. Resolution of electron microscope is 2-4 Anystrom that is 500X of compound microscope.
Correct answer: 2.0 um, 500X6978. Identify the correct order?
- A. Organ>function>cell>tissue
- B. Cell>organ>tissue>function
- C. Cell>tissue>organ>system
- D. Tissue>organ>cell>function
Explanation: The correct sequence of the structural organization of the human body is: Cell → tissue → organ → organ system.
Correct answer: Cell>tissue>organ>system6979. Germ Theory of disease was proposed by:
- A. Leeuwenhoek
- B. Louis Pasteur
- C. Walther Flemming
- D. Robert Koch
- E. Edward Jenner
Explanation: This is a fact. Robert Koch formulated the germ theory of disease.
Correct answer: Robert Koch6980. Why do some root cells have root hairs?
- A. For the maintenance of the temperature of the cell sap
- B. To increase the surface area of the cells
- C. To increase the volume of the cell sap
- D. To provide a place for cell nuclei
- E. To allow movement of soil particles
Explanation: Root hair cells improve plant water absorption by increasing root surface area to volume ratio which allows the root hair cell to take in more water.
Correct answer: To increase the surface area of the cells