Plants prepare glucose in the process of:
- A.respiration
- B.photosynthesis
- C.degradation
- D.mineral absorption
Correct answer
Explanation
The correct answer is B, photosynthesis. Green plants use sunlight, carbon dioxide and water to make glucose, giving out oxygen as a by-product.
Photosynthesis takes place mainly in the chloroplasts of leaf cells, where chlorophyll traps light energy. The overall reaction is 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ in the presence of light and chlorophyll. The glucose is used for energy, turned into starch for storage or into cellulose for cell walls. Because plants make their own food in this way, they are called autotrophs and form the base of every food chain.
A is wrong: respiration breaks glucose down to release energy; it does not make it.
C is wrong: degradation is the breaking down of substances, the opposite of making glucose.
D is wrong: mineral absorption takes up salts from the soil through roots and makes no glucose.
Exam tip: photosynthesis builds glucose and releases oxygen; respiration uses glucose and releases carbon dioxide.
Practice Questions
View allWhich one of the following plant tissues has dead cells ?
- A.Epidermis
- B.Parenchyma
- C.Collenchyma
- D.Sclerenchyma
Show answer
Sclerenchyma cells are dead at maturity, with thick walls hardened by lignin. Sclerenchyma is the tissue that makes plants hard and stiff.
Read the full explanation →Imagine a current-carrying straight conductor with magnetic field of lines in anti-clockwise direction. Then the direction of current is determined by
- A.the Right-Hand Thumb rule and it would be in the downward direction.
- B.the Left-Hand Thumb rule and it would be in the downward direction.
- C.the Right-Hand Thumb rule and it would be in the upward direction.
- D.the Left-Hand Thumb rule and it would be in the upward direction.
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For a straight wire, the right-hand thumb rule links the current to the circular field lines around it. Hold the wire in the right hand with the thumb along the current; the curled fingers then show the direction of the magnetic field lines, which form concentric circles around the wire.
Read the full explanation →Which one of the following statements is true for sound waves propagating in air?
- A.Sound is an electromagnetic wave and transverse in nature
- B.Sound is a mechanical wave and longitudinal in nature
- C.Sound is a mechanical wave and transverse in nature
- D.Sound is an electromagnetic wave and longitudinal in nature
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Sound needs a material medium to travel, and in air its particles vibrate back and forth along the direction the wave moves.
Read the full explanation →Which one of the following is primarily responsible for conduction of current in a metal?
- A.Bound electrons
- B.Free electrons
- C.Both bound and free electrons
- D.Ions
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In a metal, the outer electrons of the atoms are not tied to any one atom and drift through the lattice when a voltage is applied, carrying the current.
Read the full explanation →Which one of the following statements is correct about the magnification of an optical microscope?
- A.Magnification increases with the increase in focal length of eyepiece
- B.Magnification increases with the increase in focal length of objective
- C.Magnification does not depend upon the focal length of eyepiece
- D.Magnification decreases with the increase in focal length of eyepiece
Show answer
A compound microscope magnifies more when both its lenses have short focal lengths. In a compound microscope the objective forms a real, enlarged image, and the eyepiece magnifies it further like a simple magnifier.
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