All Free Biology MCQs with Answers
Every Biology question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
19,844 questions · page 949 of 993
- A. Chlorophyll
- B. Photosystem
- C. Photon
- D. Electron
Explanation: Photosystem is the correct option because it refers to the functional unit in the chloroplasts of plants and cyanobacteria where the…
Correct answer: Photosystem- A. 680 nm
- B. 780 nm
- C. 700 nm
- D. 580 nm
Explanation: There are two photosystems: PSI and PSII. These are named in order of their discovery.
Correct answer: 700 nm- A. ATP and CO2
- B. ATP
- C. Only CO2
- D. Only Oxygen
Explanation: Linear electron flow (LEF) in photosynthesis produces both ATP and NADPH, and the cyclic electron flow (CEF) around photosystem I has been…
Correct answer: ATP- A. Unstable 6-carbon compound
- B. Unstable 5-carbon compound
- C. Unstable 4-carbon compound
- D. Unstable 3-carbon compound
Explanation: The correct option is A, as the first unstable product formed after CO2 fixation in the Calvin Cycle is the 6-carbon compound…
Correct answer: Unstable 6-carbon compound- A. -CH3
- B. -CHO
- C. -COOH
- D. -OH
Explanation: Chlorophyll A is a bluish-green pigment that is soluble in organic solvents like acetone and alcohol.
Correct answer: -CH3- A. Mg2+
- B. Ca2+
- C. K+
- D. Na+
Explanation: Mg2+ ions are essential in making chlorophyll similar to how iron ions are substantial in making haemoglobin.
Correct answer: Mg2+- A. Membrane of mitochondria
- B. Thylakoid membrane
- C. Membrane of Smooth Endoplasmic Reticulum
- D. Membrane of Rough Endoplasmic Reticulum
Explanation: The thylakoid membrane of the chloroplasts has these light-harvesting clusters called photosystems which contain various pigments needed…
Correct answer: Thylakoid membrane18968. Carotenoids absorb light of:
- A. Yellow-orange range
- B. Yellow-red range
- C. Orange-red range
- D. Blue-violet range
Explanation: Carotenoids are one of the accessory pigments in the chloroplasts which absorb light in the Blue-Green and Violet range.
Correct answer: Blue-violet range18969. Chlorophyll 'a' and chlorophyll 'b' differ in one of the functional group. Chlorophyll 'a' has:
- A. -CHO
- B. -OH
- C. -CH3
- D. -NH2
Explanation: The only difference between chlorophyll-a and b is that chlorophyll-a has methyl (CH3) on the 2nd pyrrole ring and whereas chlorophyll-b…
Correct answer: -CH3- A. 3-carbon compound
- B. Ribulose bisphosphate
- C. 5-carbon compound
- D. 6-carbon compound
Explanation: Glycerate-3-phosphate, being a carboxylic acid, gets reduced to glyceraldehyde phosphate which is a 3-carbon compound.
Correct answer: 3-carbon compound- A. Glucose
- B. Sucrose
- C. Fructose
- D. None of the above
Explanation: Factual recall;Glucose is the monosaccharide, that makes up the disaccharide sucrose along with fructose, whereas sucrose is the form, in…
Correct answer: Sucrose18972. Given figure shows:
- A. Structure of a Lenticel
- B. Hydathode showing gaseous vapour exchange
- C. Fungus reproducing by spore formation
- D. Algae reproducing by spore formation
Explanation: The figure shows the structure of 'Lenticel', which facilitates gaseous exchange and transpiration.
Correct answer: Structure of a Lenticel- A. Apoplast Theory
- B. Symplast Theory
- C. Vacuolar Theory
- D. Cytoplasmic Theory
Explanation: The theory that describes how water and dissolved chemicals are carried through the cell wall and intercellular gaps of plants is called…
Correct answer: Apoplast Theory- A. Saprotrophic mode
- B. Parasitic mode
- C. Photosynthesis mode
- D. Obligate mode
Explanation: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy, using carbon…
Correct answer: Photosynthesis mode- A. It causes radiation pollution
- B. It is very expensive
- C. It is not long lasting
- D. It pollutes the air
Explanation: Explanation:One of the major drawbacks of nuclear energy is the risk of radiation pollution in the event of accidents, such as the…
Correct answer: It causes radiation pollution- A. Cyanobacteria
- B. Mycorrhizae
- C. Fungi
- D. Lichens
Explanation: Explanation:Correct answer is lichen as they are used as an bioindicator specifically for air pollution.
Correct answer: Lichens- A. Biosphere
- B. Atmosphere
- C. Lithosphere
- D. Hydrosphere
Explanation: [A] Biosphere is made up of the parts of earth where life exists[B] Atmosphere is the layer of gases around earth and ozone is present in…
Correct answer: Atmosphere- A. Eutrophication
- B. Photosynthesis
- C. Decomposition
- D. Recycling
Explanation: Option A is correct since Eutrophication is the process in which the water body has an enriched amount of nutrients and thus more life and…
Correct answer: Eutrophication- A. Geothermal energy
- B. Thermal energy
- C. Electric energy
- D. Solar energy
Explanation: Option A is correct since Geothermal energy is natural heat trapped underground.Option B is incorrect because Thermal energy is only heat…
Correct answer: Geothermal energy- A. Chlorine
- B. Bromine
- C. Chlorofluorocarbon
- D. Carbon
Explanation: Thinning in the ozone layer is caused by increasing concentrations of ozone-depleting chemicals - chlorofluorocarbons or CFCs (compounds…
Correct answer: Chlorofluorocarbon