The digestive enzymes are present in
- A.mitochondria
- B.vacuoles
- C.lysosomes
- D.ribosomes
Correct answer
Explanation
The correct answer is C, lysosomes. Lysosomes are small sacs bound by a membrane that are filled with digestive enzymes able to break down almost any material in the cell.
Lysosomes act as the waste disposal system of the cell. They digest worn-out cell parts and foreign material such as bacteria that enter the cell. When a cell is badly damaged, its lysosomes may burst and their enzymes digest the cell itself, which is why they are called the suicide bags of the cell. Their enzymes are made on the rough endoplasmic reticulum and packed by the Golgi apparatus.
A is wrong because mitochondria release energy as ATP through respiration and are called the powerhouse of the cell. B is wrong because vacuoles mainly store water, food and waste, and give turgidity to plant cells. D is wrong because ribosomes are the sites of protein synthesis.
Exam tip: lysosome is the suicide bag, mitochondrion the powerhouse, and ribosome the protein factory of the cell.
Practice Questions
View allWhich one of the following is monatomic?
- A.Hydrogen
- B.Sulphur
- C.Phosphorus
- D.Helium
Show answer
A monatomic element exists as single, separate atoms. Helium is a noble gas of group 18: its only shell, the first, is full with two electrons, so a helium atom has no tendency to share or transfer electrons and does not bond even with another helium atom.
Read the full explanation →The normal systolic pressure in human beings is :
- A.80 mm of Hg
- B.100 mm of Hg
- C.120 mm of Hg
- D.140 mm of Hg
Show answer
Blood pressure is written as two numbers, and normal adult blood pressure is about 120/80 mm of mercury.
Read the full explanation →'Study of human societies and cultures from the oldest times to the present' is the work of
- A.Archaeologists
- B.Anthropologists
- C.Palaeontologists
- D.Geologists
Show answer
Anthropology, from the Greek 'anthropos' (human) and 'logos' (study), is the science of human beings: how societies and cultures began, how they changed and how people live today.
Read the full explanation →Which of the following catalytic systems is used for the reduction of unsaturated hydrocarbon to saturated hydrocarbon?
- A.Copper and H2
- B.Iron and H2
- C.Zinc and H2
- D.Nickel and H2
Show answer
Adding hydrogen across the double or triple bond of an alkene or alkyne turns it into a saturated alkane; this reaction is called hydrogenation and it needs a catalyst.
Read the full explanation →Which one among the following is not a plant hormone ?
- A.Gibberellins
- B.Abscisic acid
- C.Auxins
- D.Thyroxine
Show answer
Thyroxine is an animal hormone, made by the thyroid gland in the neck, and it controls the rate of metabolism in the human body.
Read the full explanation →