Which organelle in animal cells can digest foreign materials?
- A.Endoplasmic reticulum
- B.Lysosome
- C.Golgi body
- D.Mitochondria
Correct answer
Explanation
The correct answer is B, Lysosome. Lysosomes are membrane-bound sacs of digestive enzymes that break down foreign material such as bacteria and worn-out cell parts.
Lysosomes are formed by the Golgi apparatus and contain hydrolytic enzymes that work in an acidic interior. When a white blood cell engulfs a bacterium, the vesicle fuses with lysosomes, whose enzymes digest it. Lysosomes also remove old or damaged organelles. If a cell is badly damaged, its lysosomes may burst and digest the cell itself, which is why they are called the suicide bags of the cell.
A is wrong: the endoplasmic reticulum is a network of membranes that makes and transports proteins and lipids.
C is wrong: the Golgi body packages and dispatches materials and helps form lysosomes, but does not itself digest foreign matter.
D is wrong: mitochondria carry out cellular respiration and release energy as ATP, earning the name powerhouse of the cell.
Exam tip: lysosome = suicide bag (digestion); mitochondria = powerhouse; Golgi = packaging centre; ribosome = protein factory.
Practice Questions
View allThe speed of the wind is measured by
- A.wind vane
- B.wind rose
- C.barometer
- D.anemometer
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An anemometer measures how fast the wind is blowing; its name comes from the Greek word anemos, meaning wind.
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- A.interference of light
- B.diffraction of light
- C.polarization of light
- D.total internal reflection of light
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Light that enters a cut diamond is reflected again and again inside it before it escapes, which makes the stone sparkle.
Read the full explanation →Which one of the following is NOT an electromagnetic wave ?
- A.Light wave
- B.Radio wave
- C.Sound wave
- D.Micro wave
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Sound is a mechanical wave that needs a medium to travel, while the other three are electromagnetic waves. Sound travels as a longitudinal wave of compressions and rarefactions in air, water or solids, which is why it cannot pass through a vacuum.
Read the full explanation →Which one of the following is NOT true for an electromagnetic wave ?
- A.Electromagnetic wave transports energy and momentum
- B.Electromagnetic wave can be polarized and reflected
- C.Electromagnetic wave is longitudinal
- D.Electromagnetic wave propagation is described by the varying electric and magnetic fields
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Electromagnetic waves are transverse, not longitudinal, so this statement is false. In an electromagnetic wave the electric field and the magnetic field oscillate at right angles to each other and both at right angles to the direction in which the wave travels.
Read the full explanation →Which one of the following frequency ranges is sensitive to human ears ?
- A.0-200 Hz
- B.20-20,000 Hz
- C.200-20,000 Hz only
- D.2,000-20,000 Hz only
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The normal human ear hears sound from about 20 hertz to 20,000 hertz, the audible range. Frequency, measured in hertz, is the number of vibrations per second, and it decides the pitch of a sound: the higher the frequency, the shriller the note.
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