All Free Biology MCQs with Answers
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19844 questions · page 669 of 1985
6681. Plastids are only found in:
- A. Animals and Plants
- B. Animals
- C. Plants
- D. Viruses
Explanation: Plastids are present in autotrophic eukaryotes and multicellular organisms such as plants and algae. Animals are heterotrophs and viruses are not considered as living organisms.
Correct answer: Plants6682. What is the plasma membrane chemically composed of?
- A. Phospholipids only
- B. Lipids and proteins
- C. Lipids and carbohydrates
- D. Glycoproteins
Explanation: The plasma membrane is made up 60-80 % of proteins, 20-40 % of lipids and a very small amount of carbohydrates.
Correct answer: Lipids and proteins6683. The endoplasmic reticulum contains a system of flattened membrane-bounded sacs which are called?
- A. Cristae
- B. Marks
- C. Cisternae
- D. Tubules
Explanation: The material in the Endoplasmic reticulum is separated from the cytoplasmic materials by spherical or tubular membranes called cisternae.
Correct answer: Cisternae6684. Which organelle synthesizes enzymes?
- A. Mitochondria
- B. Vacuole
- C. Rough endoplasmic reticulum
- D. Ribosomes
Explanation: Most of the enzymes are protein molecules and are synthesized on the ribosomes.
Correct answer: Ribosomes6685. Ribosomes exist in two forms. They are either attached with the RER or freely dispersed in the _
- A. Tonoplast
- B. Golgi bodies
- C. Cytoplasm
- D. SER
Explanation: Therefore, the correct answer is C) Cytoplasm, as ribosomes can exist freely dispersed in the cytoplasm when not attached to the rough endoplasmic reticulum (RER).
Correct answer: Cytoplasm6686. Which model of the plasma membrane suggests that proteins are embedded in lipid bilayer?
- A. Unit membrane
- B. Fluid mosaic
- C. Permeable
- D. Ultracentrifuge
Explanation: Therefore, the correct answer is B) Fluid Mosaic, which suggests that proteins are embedded in the lipid bilayer of the plasma membrane.
Correct answer: Fluid mosaic6687. Lipid metabolism is the function of which organelle?
- A. Mitochondria
- B. Sarcoplasmic reticulum
- C. RER
- D. SER
Explanation: Therefore, the correct answer is D) SER (Smooth Endoplasmic Reticulum), which is the organelle primarily responsible for lipid metabolism.
Correct answer: SER6688. The enzymes of lysosomes are synthesized in the _.
- A. RER
- B. SER
- C. Chloroplast
- D. Golgi apparatus
Explanation: Therefore, the correct answer is A) RER, as it is the organelle where lysosomal enzymes are synthesized and processed before being transported to lysosomes.
Correct answer: RER6689. How many microtubules is the centriole made up of?
- A. 9
- B. 27
- C. 3
- D. 12
Explanation: Each centriole is made of nine microtubule triplets (9x3=27)
Correct answer: 276690. This cell which is the longest in the human body:
- A. Muscle cells
- B. Nerve cells
- C. Bone cells
- D. Gland cells
Explanation: The nerve cells or neurons are the longest cells in the human body with some neurons being as long as 1-1.5 meters. These cells are responsible for transmitting signals throughout the body
Correct answer: Nerve cells