1. Which component of the bacterial lac operon serves as the binding site for RNA polymerase?

  • A. Regulator gene (i)
  • B. Operator (O)
  • C. Promoter (P)
  • D. Structural gene (Z)

Answer: C. Promoter (P)

Explanation: RNA polymerase binds to the promoter region to initiate transcription of the structural genes.

2. Which of the following valves prevents the backflow of blood from the pulmonary artery into the right ventricle?

  • A. Tricuspid valve
  • B. Mitral valve
  • C. Pulmonary semilunar valve
  • D. Aortic semilunar valve

Answer: C. Pulmonary semilunar valve

Explanation: The pulmonary semilunar valve ensures one-way blood flow from the right ventricle to the pulmonary artery.

3. Which hormone secreted by the adrenal medulla prepares the body for emergency situations?

  • A. Aldosterone
  • B. Cortisol
  • C. Adrenaline (Epinephrine)
  • D. Thyroxine

Answer: C. Adrenaline (Epinephrine)

Explanation: Adrenaline triggers the "fight-or-flight" response by increasing heart rate, blood pressure, and blood glucose levels.

4. The stop codons in the genetic code are:

  • A. AUG, UUU, UAA
  • B. UAA, UAG, UGA
  • C. AUG, UGG, UGA
  • D. UUC, UUA, UAG

Answer: B. UAA, UAG, UGA

Explanation: UAA (ochre), UAG (amber), and UGA (opal) are the three termination codons that do not code for any amino acid.

5. Which plasma protein is mainly responsible for maintaining the osmotic pressure of blood?

  • A. Fibrinogen
  • B. Globulin
  • C. Albumin
  • D. Prothrombin

Answer: C. Albumin

Explanation: Albumin is the most abundant plasma protein and plays a major role in maintaining colloidal osmotic pressure.

6. Which scientist first coined the term "ecology"?

  • A. Charles Elton
  • B. Ernst Haeckel
  • C. Eugene Odum
  • D. Charles Darwin

Answer: B. Ernst Haeckel

Explanation: Ernst Haeckel coined the term "ecology" in 1866 to describe the study of relationships between organisms and their environment.

7. Which phase of mitosis is characterized by the splitting of centromeres and movement of sister chromatids toward opposite poles?

  • A. Prophase
  • B. Metaphase
  • C. Anaphase
  • D. Telophase

Answer: C. Anaphase

Explanation: During anaphase, centromeres divide and sister chromatids migrate to opposite poles with the help of spindle fibres.

8. Which of the following is the correct sequence of taxonomic hierarchy from lower to higher category?

  • A. Species → Genus → Family → Order → Class
  • B. Family → Genus → Species → Order → Class
  • C. Species → Family → Genus → Order → Class
  • D. Genus → Species → Family → Order → Class

Answer: A. Species → Genus → Family → Order → Class

Explanation: The taxonomic hierarchy ascends as Species → Genus → Family → Order → Class → Phylum/Division → Kingdom.

9. Which plant hormone is commonly known as the "stress hormone" in plants?

  • A. Auxin
  • B. Cytokinin
  • C. Abscisic acid (ABA)
  • D. Gibberellin

Answer: C. Abscisic acid (ABA)

Explanation: ABA helps plants tolerate drought and other environmental stresses by inducing stomatal closure and seed dormancy.

10. Which of the following is an example of a polysaccharide used for energy storage in animals?

  • A. Cellulose
  • B. Chitin
  • C. Glycogen
  • D. Pectin

Answer: C. Glycogen

Explanation: Glycogen is the storage polysaccharide in animals and is primarily stored in the liver and skeletal muscles.