2: The Cell as the Basic Unit of Life - Problems

Question 1

Which of the following about inorganic ions in organisms is correct?

A: magnesium is a component of teeth.
B: nitrate is a source of nitrogen for the synthesis of proteins.
C: calcium is a component of chlorophyll.
D: iron is a component of bones.

Answer 1

B

Magnesium is a component of chlorophyll and calcium is a component of teeth.
Iron is a component of haemoglobin.

Question 2

Which of the following are the functions of carbohydrates in organisms? (multiple choice)

(1) makes up cell walls
(2) provides energy
(3) regulates chemical reactions

Answer 2

(1) (2)

Question 3

Which of the following is stated in the Cell Theory?

(A) All organisms have similar chemical constituents.
(B) Cells vary in size and shape.
(C) All cells contain DNA as their genetic material.
(D) All cells come from pre-existing cells.

Answer 3

D

Question 4

(CE 2006 II Q39)
The observation of cells using a light microscope led to…

(A) the discovery of virus.
(B) the formulation of the cell theory.
(C) the discovery of bacteria as a disease-causing agent.
(D) the discovery of the fine structure of cell organelles.

Answer 4

B

Question 5

Arrange the steps for observing a specimen using a light microscope under low-power magnification into the correct sequence.

(1) Turn the coarse adjustment knob to lower the stage.
(2) Turn the coarse adjustment knob to raise the stage.
(3) Turn the fine adjustment knob.
(4) Rotate the nosepiece to select a low-power objective.
(5) Clip the slide on the stage.

Answer 5

(4) (5) (2) (1) (3)

Question 6

A student is observing a tissue under a light microscope. Which of the following combinations of eyepiece and objective allows him to see the largest number of cells in the field of view?

(A) 10X eyepiece, 10X objective
(B) 10X eyepiece, 40X objective
(C) 15X eyepiece, 4X objective
(D) 15X eyepiece, 40X objective

Answer 6

C

Question 7

True or false:
All plant cells have chloroplasts.

Answer 7

False

Question 8

True or false:
All plant cells have a large central vacuole.

Answer 8

False

Question 9

Which of the following comparisons between a prokaryotic cell and an eukaryotic cell is correct?

(A) Prokaryotic cells have no nucleic acid.
(B) Both have cell wall.
(C) Both have a nuclear membrane.
(D) Both have ribosomes.

Answer 9

D

Question 10

A piece of leaf epidermis is being observed under a light microscope.

What are the actions to be taken to observe one of the cells in more detail?

Answer 10

Move the slide until the cell is located in the centre of the field of view. Rotate the nosepiece to select an objective of higher magnification. Focus by turning the fine adjustment knob.

Question 11

(CE 2008 I Q4c)
A temporary slide of onion epidermis is prepared.

What is the purpose of staining the onion with iodine solution?

Answer 11

To make the cell structures more distinct (and observable).

Question 12

(CE 2008 I Q4c)
A temporary slide of onion epidermis is prepared.

What is the step such that the tissue is flattened?

Answer 12

Cover the tissue with a cover slip.

Question 13

Suggest why mitochondria cannot be observed in a photomicrograph of a cell under a light microscope.

Answer 13

The magnification and resolution of the light microscope may be not high enough.

Question 14

Describe how chloroplasts and mitochondria in a plant cell work together so that the cell can obtain energy in usable form to perform its functions.

Answer 14

Chloroplasts captures light energy and converts it into chemical energy in the form of carbohydrates in the process of photosynthesis.
Carbohydrates is broken down in respiration at the mitochondria, which releases the energy in a usable form.

Question 15

State the purpose of staining cells in microscopic observation.

Answer 15

Staining cells can increase the colour contrast between cellular structures so that different cell structures can be observed more clearly.

Question 16

The table below shows the relative abundance of mitochondria and rough endoplasmic reticulum in four cells (W, X, Y, Z).

Which cell is likely to be the muscle cell and which one is likely to be the white blood cell? Explain.

Answer 16

Z is likely to be the muscle cell. It has a large amount of mitochondria to meet the energy requirement of muscle contraction.
Y is likely to be the white blood cell. It has a large amount of rough endoplasmic reticulum for producing antibodies which are made up of proteins.

Question 17

The table below shows the relative abundance of mitochondria and rough endoplasmic reticulum in four cells (W, X, Y, Z).

A student suggests that W may be a bacterial cell. Give one piece of evidence from the table to support the claim.

Answer 17

According to the table, W contains no mitochondria or rough endoplasmic reticulum. Both are membrane-bound organelles. A bacterial cell, which is a prokaryotic cell, does not contain membrane-bound organelles.

Question 18

The electron micrograph below shows some part of a cell.

Is this cell an eukaryotic cell of a prokaryotic cell? Give one piece of evidence from the electron micrograph to support the answer.

Answer 18

This cell is an eukaryotic cell. Mitochondria, which are bounded by a double membrane, can be observed in the electron micrograph.

Question 19

The pie charts show the total membrane surface areas of mitochondria and rough endoplasmic reticulum relative to the total membrane surface areas of all organelles in two types of human cells.
X: mitochondria
Y: rough endoplasmic reticulum

With reference to the functions of liver cells, explain why the total membrane surface area of mitochondria is higher in liver cells.

Answer 19

Liver cells have a high level of metabolic activities. A lot of energy is required to support their activities. They need a larger number of mitochondria to meet the energy requirement because mitochondria is the site for respiration.

Question 20

The pie charts show the total membrane surface areas of mitochondria and rough endoplasmic reticulum relative to the total membrane surface areas of all organelles in two types of human cells.
X: mitochondria
Y: rough endoplasmic reticulum

State one piece of evidence from the pie charts that cell Z may produce more proteins than the liver cell and explain.

Answer 20

Cell Z has a larger total membrane surface area of rough endoplasmic reticulum. This means it has a larger amount of rough endoplasmic reticulum. Rough endoplasmic reticulum is the site for the synthesis of proteins. A larger amount of rough endoplasmic reticulum indicates cell Z may produce more protein.