Bats detect obstacles in their path by receiving the reflected
- A.Infrasonic waves
- B.Ultrasonic waves
- C.Radio waves
- D.Microwaves
Correct answer
Explanation
The correct answer is B, Ultrasonic waves. Bats send out ultrasonic squeaks and listen for the echoes to locate obstacles and prey.
This method is called echolocation. A bat emits short pulses of sound above 20,000 hertz, beyond the range of human hearing. The waves strike an object and bounce back, and from the time the echo takes and its direction the bat judges the distance, size and movement of the object, even in total darkness. Dolphins use the same method under water, and ships copy it in SONAR, which uses ultrasound to find the depth of the sea and underwater objects.
A is wrong: infrasonic waves are below 20 hertz and are used by elephants and whales to call over long distances, not by bats to find obstacles. C is wrong: radio waves are electromagnetic waves used in RADAR and broadcasting, and animals do not emit them. D is wrong: microwaves are also electromagnetic, used in ovens and RADAR, not produced by bats.
Exam tip: Human hearing is 20 Hz to 20 kHz; below is infrasonic, above is ultrasonic; bats, dolphins and SONAR use ultrasound.
Practice Questions
View allThe valency of phosphorus is
- A.2, 3
- B.3, 4
- C.4, 5
- D.3, 5
Show answer
Phosphorus has five electrons in its outer shell and shows two common valencies, 3 and 5. Phosphorus, atomic number 15, has the electronic configuration 2, 8, 5.
Read the full explanation →Which one of the following statements is NOT correct ?
- A.Single celled eukaryotes belong to Kingdom Protista
- B.Yeast, a fungus is multicellular
- C.The fungi constitute a unique kingdom of heterotrophs
- D.Ascomycetes, a saprophytic fungi is multicellular or rarely unicellular
Show answer
This statement is false, because yeast is one of the few fungi that are unicellular. In Whittaker's five-kingdom system, fungi form a separate kingdom.
Read the full explanation →Desalination of seawater is done by using reverse osmosis. The pressure applied to the solution is
- A.larger than osmotic pressure
- B.smaller than osmotic pressure
- C.equal to osmotic pressure
- D.equal to atmospheric pressure
Show answer
Only a pressure greater than the osmotic pressure of seawater can push pure water backwards through the membrane. In ordinary osmosis, water moves through a semipermeable membrane from the dilute side to the concentrated side.
Read the full explanation →Which one of the following does not form oxide on reaction with oxygen?
- A.Magnesium
- B.Lead
- C.Tin
- D.Silver
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Silver sits near the bottom of the reactivity series and does not combine with oxygen even when heated in air.
Read the full explanation →The foul smell of urine of a healthy man having healthy food, when spilled on floor, is mainly due to the bacterial decomposition of
- A.urea into sulphur dioxide
- B.sugar into carbon dioxide
- C.lipids into methane
- D.urea into ammonia
Show answer
Bacteria on the floor break down the urea in urine and release ammonia, which has a sharp, pungent smell. Urea, CO(NH2)2, is the main nitrogenous waste of humans.
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