The term 'Probiotic' is applied to
- A.Organic food
- B.Antacid
- C.Antibiotic
- D.Live microbial food supplement
Correct answer
Explanation
The correct answer is D, Live microbial food supplement. Probiotics are live, helpful microbes taken in food or supplements to improve the balance of bacteria in the gut.
The word means "for life", the opposite of antibiotic, "against life". The most common probiotics are bacteria of the genera Lactobacillus and Bifidobacterium, and the yeast Saccharomyces boulardii. They are found in curd, yoghurt, buttermilk, kefir and some fermented foods, and are also sold as capsules or drinks. Taken in adequate amounts, they help digestion, can reduce diarrhoea caused by antibiotics and support the body's immunity. Prebiotics, by contrast, are fibres that feed these good bacteria.
A is wrong: organic food is food grown without synthetic fertilisers and pesticides, which has nothing to do with live microbes. B is wrong: an antacid is a base, such as magnesium hydroxide, that neutralises excess stomach acid. C is wrong: an antibiotic kills or stops the growth of bacteria, which is the opposite of what a probiotic does.
Exam tip: probiotic = live good microbes (curd, Lactobacillus); prebiotic = food for them; antibiotic = kills bacteria.
Practice Questions
View allA negative work is done when an applied force F and the corresponding displacement S are
- A.perpendicular to each other.
- B.parallel to each other.
- C.anti-parallel to each other.
- D.equal in magnitude.
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Work is negative when the force acts opposite to the displacement, because the angle between them is then 180°. Work done is W = F S cos θ, where θ is the angle between the force and the displacement.
Read the full explanation →Which one of the following statements about a satellite orbiting around the Earth is correct ?
- A.Satellite is kept in orbit by remote control from ground station.
- B.Satellite is kept in orbit by retro-rocket and solar energy keeps it moving around the Earth.
- C.Satellite requires energy from solar panels and solid fuels for orbiting.
- D.Satellite does not require any energy for orbiting.
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Once a satellite is placed in orbit with the right speed, the Earth's gravity keeps it going round without any engine.
Read the full explanation →Which one of the following is not a conservative force ?
- A.Frictional force
- B.Electric force
- C.Gravitational force
- D.Spring force
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Friction is a non-conservative force because the work it does depends on the path taken and the energy it removes is lost as heat.
Read the full explanation →A microphone converts
- A.electrical signals to sound waves
- B.sound waves to electrical signals
- C.microwaves to sound waves
- D.sound waves to microwaves
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A microphone is a transducer that changes the pressure variations of sound into a matching electrical signal. In a common dynamic microphone, sound waves make a thin diaphragm vibrate.
Read the full explanation →When a light ray passes through from air to water with a non-zero angle the ray will be
- A.bending towards the normal
- B.bending away from the normal
- C.propagating in straight line
- D.reflected towards the opposite direction
Show answer
Light slows down when it enters water from air, so a ray that strikes the surface at an angle bends towards the normal.
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