In which one of the following physiological processes, excess water escapes in the form of droplets from a plant?
- A.Transpiration
- B.Guttation
- C.Secretion
- D.Excretion
Correct answer
Explanation
The correct answer is B, Guttation. Guttation is the loss of water in the form of liquid droplets from the edges and tips of leaves.
Guttation happens mostly at night or early in the morning, when the soil is moist and the air is humid, so transpiration is slow. Water keeps entering the roots, root pressure builds up, and the extra water is pushed out through special pores called hydathodes at the leaf margins. The drops seen on the tips of grass blades in the morning are often guttation, not dew. Plants such as tomato, grasses and Colocasia show it clearly. The guttation fluid also carries dissolved salts and sugars.
A is wrong because transpiration removes water as vapour, mainly through stomata, not as droplets. C is wrong because secretion is the release of useful substances such as nectar or enzymes. D is wrong because excretion is the removal of waste products, not the escape of surplus water.
Exam tip: water as vapour through stomata is transpiration; water as droplets through hydathodes, driven by root pressure, is guttation.
Practice Questions
View allThe mass number of an element is NOT changed when it emits
- A.Alpha and Beta radiations only
- B.Alpha and Gamma radiations only
- C.Beta and Gamma radiations only
- D.Alpha, Beta and Gamma radiations
Show answer
Neither beta nor gamma emission changes the total number of protons and neutrons in a nucleus, so the mass number stays the same.
Read the full explanation →Which one among the following statements about facilitated transport in plants is correct?
- A.All passive transports are types of facilitated transport.
- B.Facilitated transport is an example of active transport.
- C.Water moves across plasma membrane by active transport.
- D.Facilitated transport requires assistance of carrier proteins.
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In facilitated transport, molecules cross the membrane with the help of membrane proteins, while still moving down their concentration gradient.
Read the full explanation →Who among the following has coined the term 'Quark', the fundamental particles that make up protons and neutrons in an atomic nucleus ?
- A.Richard Feynman
- B.Murray Gell-Mann
- C.Albert Einstein
- D.Niels Bohr
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The American physicist Murray Gell-Mann proposed quarks in 1964 and gave them their name. Gell-Mann, and independently George Zweig, suggested that protons, neutrons and other such particles are built from smaller units.
Read the full explanation →The spindle fibre is attached to which of the following specific regions of the chromosomes?
- A.Kinetochore
- B.Chromonema
- C.Telomere
- D.Centriole
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Spindle fibres attach to the kinetochore, a disc-shaped protein structure on the centromere of each chromosome. During cell division the spindle, made of microtubules, pulls the copies of each chromosome apart.
Read the full explanation →Which one of the following is the chemical name of heavy water?
- A.Hydrogen oxide
- B.Deuterium dioxide
- C.Deuterium oxide
- D.Heavy hydrogen oxide
Show answer
Heavy water is D₂O: two atoms of deuterium joined to one atom of oxygen. Deuterium is the isotope of hydrogen with one proton and one neutron in its nucleus, so it is about twice as heavy as ordinary hydrogen.
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