Which one of the following statements about animal cells and plant cells is correct?
- A.Animal cells have only cell membrane not cell wall, whereas plant cells have only cell wall not cell membrane.
- B.Animal cells have only cell membrane not cell wall, but plant cells have both.
- C.Both animal and plant cells have cell membrane and cell wall.
- D.Only some cells of animals have cell wall and all plant cells have cell membrane.
Correct answer
Explanation
The correct answer is B, animal cells have only a cell membrane, but plant cells have both. Every living cell needs a cell membrane, and plant cells add a rigid cell wall outside it.
The cell membrane, or plasma membrane, is the thin, selectively permeable boundary of every cell; it controls what enters and leaves. In plant cells it lies just inside the cell wall, which is made mainly of cellulose, gives the cell a fixed shape and lets it withstand the pressure of water inside. Fungi also have walls, of chitin, and bacteria have walls of peptidoglycan. Animal cells have no wall, which is why their shapes vary and many can move or change form.
A is wrong because plant cells do have a cell membrane beneath the wall.
C is wrong because animal cells never have a cell wall.
D is wrong because no animal cells have a cell wall.
Exam tip: plant wall is cellulose, fungal wall chitin, bacterial wall peptidoglycan; animal cells have none.
Practice Questions
View allWhich of the following are nitrogen-fixing plants?
1. Alfalfa
2. Amaranth
3. Chickpea
4. Clover
5. Purslane (Kulfa)
6. Spinach
Select the correct answer using the code given below:
- A.1, 3 and 4 only
- B.1, 3, 5 and 6 only
- C.2, 4, 5 and 6 only
- D.1, 2, 4, 5 and 6
Show answer
Alfalfa, chickpea and clover are legumes, and legumes fix nitrogen. Plants of the legume family (Fabaceae) carry root nodules that house Rhizobium bacteria.
Read the full explanation →The 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.
Show answer
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
Show answer
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
Show answer
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 →