Tag: cell-the basic unit of life

Questions Related to cell-the basic unit of life

Cell size in unicellular organisms is 

  1. 0.5-10 micrometer

  2. 1.5-2.0 micrometer

  3. 2.5-3.0 micrometer

  4. 3.5-4.0 micrometer


Correct Option: A
Explanation:
  • The cell is the structural unit of life. Unicellular organisms are made up of one cell that performs all the functions. Its size is 0.5-10 micrometers, whereas, in multicellular organisms, cell size is 10-100 micrometers.

Longest cells in human body are________.

  1. Nerve cells.

  2. Bone cells.

  3. Leg muscle cells.

  4. Heart muscle cells.


Correct Option: A
Explanation:
ANSWER
The length of the muscle cell is 1-40 micrometers.
Nerve cells possess a cell body and one to many thin, fiber-like axons.
Some nerve cells possess axons as long as 1 meter. 
Therefore, option A is correct.

Large plant cells are

  1. Xylem vessel cells.

  2. Parenchyma cells.

  3. Sieve tube cells.

  4. Sclerenchyma fibres.


Correct Option: D
Explanation:

Sclerenchyma, in plants, support tissue composed of any of various kinds of hard woody cells. Mature sclerenchyma cells are usually dead cells that have heavily thickened secondary walls containing lignin. The cells are rigid and nonstretchable and are usually found in nongrowing regions of plant bodies, such as the bark or mature stems. Sclerenchyma is one of the three types of ground, or fundamental, tissue in plants.Sclerenchyma fibers can be found below the epidermis of monocotyledons, organized in two or three layers of cells. They are known as cortical fibers. Thus correct option is D.

Human egg is larger than human sperm because it has

  1. Larger nucleus.

  2. More membranes.

  3. Core cytoplasm.

  4. All of the above.


Correct Option: C
Explanation:

Human sperm consists of a head and tail, the head carrying the genetic material and tail has mitochondria which derives the movement of sperm. It is very small in size (0.05mm) and a drop of serum contains millions of sperms. The human egg consists of genetic material along with core cytoplasm surrounding nucleus that has all the cellular components such as ribosomes, RNAs which are essential for protein synthesis and which ultimately gives rise to the whole body of an organism. Human egg measures 2cm against human sperm 0.05mm.

The smallest animal egg is that of

  1. Ostrich

  2. Human female

  3. Duck

  4. Hen


Correct Option: B
Explanation:

The egg size of Ostrich egg is 15cm, duck egg is typically larger than hen eggboth of which are roughly between 3-10cm. Human female egg is very small about 1-2cm and hence the smallest egg among all other options.

Largest animal cell is that of

  1. Ostrich.

  2. Duck.

  3. Human.

  4. Hen.


Correct Option: A
Explanation:
Multicellular eukaryotes have a cell size in the range of 5 to 100μm. Largest cells are animal eggs. Largest egg of a land animal is that of ostrich (17 cm x 15 cm), while for an aquatic animal, it is that of whale shark (30 cm in diameter).
Thus, the correct answer is option A.

Efficient large-sized cells should be_________.

  1. Elongated.

  2. Branched.

  3. With membrane extensions.

  4. Any of the above.


Correct Option: D

Size of Acetobularia is

  1. $10cm$

  2. $10mm$

  3. $1.0mm$

  4. $0.1mm$


Correct Option: A
Explanation:

Acetabularia is a single-celled eukaryotic photosynthetic green alga. Although it is single cells it has a complex structure with size varying from 0.5-10cm. It is divided into three anatomical parts with basal rhizoid like structure resembling roots, long stalk-like structure and top umbrella that may fuse to form the cap.  

Which of the following statement are false?
(a) Most cells are tiny with volume range of $1-100$ $n{m}^{3}$
(b) Some cells have microvelli to increase the absorptive surface area.
(c) All cells arise from pre-existing cells.
(d) In plants, translocation of solutes is performed by xylem vessels and tracheids.
(e) According to cell theory, all cells arise from abiotic material.

  1. a), c) and e) are false.

  2. a), d) and e) are false.

  3. b), c) and d) are false.

  4. c), d) and e) are false.


Correct Option: B

Assume a spherical mammalian cell has a diameter of 27 microns. If a polypeptide chain with alpha helical conformation has to stretch across the cell, how many amino acids should it be comprised of?

  1. 18000

  2. 1800

  3. 27000

  4. 12000


Correct Option: A