Tag: cell-the basic unit of life

Questions Related to cell-the basic unit of life

What are the three major functional regions of a cell?

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. (i) Plasma membrane, (ii) Cytoplasm and (iii) Nucleus

  2. (i) Plasma membrane, (ii) Lysosome and (iii) Ribosome

  3. (i) Cell wall, (ii) Lysosome and (iii) Ribosome

  4. (i) Cell wall, (ii) Cytoplasm and (iii) Nucleus

Show answer
Correct Option: A
Explanation:

There are three major functional parts of the cell such as plasma membrane, cytoplasm and nucleus. Plasma membrane regulates the particles entering or leaving the cell. It carries out endocytosis, exocytosis and transport of various substances through different carrier proteins. It is also involved in cell signaling. 
Cytoplasm is a gel-like substance present in all cells. All of the cell organelles are suspended in the cytoplasm. Most of the cellular activities as metabolic pathways like glycolysis, key processes like cell division occur in the cytoplasm. Nucleus regulates all the cellular activities by controlling the enzymes required for cellular processes. The four main cellular functions of the cell are protein synthesis, cell division, growth and differentiation are carried out by the nucleus. 

So, the correct answer is option A.

Which of the following carries steroid hormone receptors?

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. Plasma membrane

  2. Endoplasmic reticulum

  3. Nucleus

  4. Cytosol

  5. None of the above

  6. Both C & D

Show answer
Correct Option: F
Explanation:

Steroid hormone receptors are found in the nucleus and cytosol. They are intra-cellular receptors responsible for the process of signal transduction. 

A nucleus is absent in the mature

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. Sieve tube cells.

  2. Mammalian erythrocytes.

  3. Monocytes.

  4. Both A and B.

Show answer
Correct Option: D
Explanation:

Sieve tubes are cells of phloem found in certain plants and help in long distance translocation and distribution. Their nucleus is fragmented and disappeared. Mammalian erythrocytes also called as red blood cells are formed in bone marrow from multipotential hemocytoblast and further converted to erythroblast (normoblast). The nucleus and mitochondria of erythroblast disappear and it is converted to mature erythrocyte with haemoglobin. Erythrocytes cannot multiply as they lack the nucleus and can survive for 100-120 days. Monocytes are immune cells of the human body and are capable of dividing into macrophages. So they have the well-defined nucleus. So nucleus is absent in sieve tube cells and mammalian erythrocytes.

A eukaryotic organelle that can best be seen with the light microscope is the:

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. Endoplasmic reticulum

  2. Nucleus

  3. Polyribosome

  4. Microtubule

Show answer
Correct Option: B
Explanation:

The nucleus is membrane-bound organelles which are seen under a light microscope because of its large size. These are spherical in shape and encompasses nuclear membrane, chromosomes, nucleoplasm and nucleolus. It contains the cell's genetic material.

Hence, the correct answer is 'Nucleus'.

How many membranes comprise the nuclear envelope?

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. One

  2. Two

  3. Three

  4. None

Show answer
Correct Option: B
Explanation:

The nuclear envelope is a membrane barrier that separates the nucleus from the cytoplasmic in eukaryotic cells. It contains a large number of proteins. The nuclear envelope is composed of two concentric bilayer membranes. The two layers are fused together into numerous tiny holes called the nuclear pores.

Hence, the correct answer is 'Two'.

The nucleus is not important as the site of:

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. DNA synthesis

  2. RNA synthesis

  3. Synthesis of ribosomal subunits

  4. Protein synthesis

Show answer
Correct Option: D
Explanation:

The nucleus is a spherical organelle which is present in eukaryotic cells. The main function of the nucleus is to control gene expressions. It synthesizes RNA and DNA. Protein synthesis takes place in Ribosomes in the cytoplasm

Hence, the correct answer is 'Protein synthesis'.

Which of these is not found in the nucleus?

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. Nucleoplasm instead of cytoplasm

  2. Functioning ribosomes

  3. Chromatin that condenses to chromosomes

  4. Nucleolus that produces rRNA

Show answer
Correct Option: B

Acetabularia used in Hammerling's nucleocytoplasmic experiments is

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. Unicellular fungus

  2. Multicellular fungus

  3. Unicellular uninucleate green alga

  4. Unicellular multinucleate green alga

Show answer
Correct Option: C
Explanation:

  • Acetabularia is a genus unicellular or single-celled green algae belonging to the family Polyphysaceae which are found in subtropical waters.

  • They are gigantic in size and complex in form, therefore, used in experiments in cell biology.
  • Hammerling's nucleocytoplasmic experiments state that the cytoplasm is the centre for all the metabolic activities in the cell and the nucleus is the controlling centre. 
  • So, the correct answer is 'Unicellular uninucleate green alga'.

Hammerling's experiments on Acetobularia involved exchanging

biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

  1. Cytoplasm

  2. Nucleus

  3. Rhizoid and stalk

  4. Gametes.

Show answer
Correct Option: C
Explanation:
  • Acetabularia cell is composed of three segments: the "rhizoid" or base which contains the nucleus, the "stalk," and the "cap." 
  • In his experiments, Hammerling grafted the stalk of one species of Acetabularia onto the rhizoid of another species. In all cases, the cap that eventually developed on the grafted cell matched the species of the rhizoid rather than that of the stalk.
  • This experiment shows that the base is responsible for the type of cap that grows. The nucleus that contains genetic information is in the base, so the nucleus directs cellular development.
  • So, the correct option is 'Rhizoid and stalk'.

Match column I with column II and select the correct option from the codes given below.

Column - I Column - II
A. Leeuwenhoek (i) First saw and described a living cell
B. Robert Brown (ii) Presence of cell wall is unique to plant cells
C. Schleiden (iii) Discovered the nucleus
D. Schwann (iv) All plants are composed of different kinds of cell
bio-chemistry cell-the basic unit of life introduction to cell discovery and cell theory cell discovery cell discovery and cell theory cell as structural and functional unit

  1. $A - (i), B - (iii), C - (iv), D - (ii)$

  2. $A - (i), B - (iii), C - (ii), D - (iv)$

  3. $A - (iii), B - (i), C - (iv), D - (ii)$

  4. $A - (i), B - (iv), C - (ii), D - (iii)$

Show answer
Correct Option: A
Explanation:
  • The first man to witness a live cell under a microscope was Anton Von Leeuwenhoek.
  • Robert Brown was responsible for discovering the nucleus of a cell.
  • Matthias Jakob Schleiden started that all parts of the plant organism are composed of different kinds of cell.
  • Theodor Schwann studied that cells had a thin outer layer which is today known as plasma membrane. He also concluded that the plant shows the presence of a cell wall is a unique character of plant cells.
  • So, the correct option is " A-(i), B-(iii), C-(iv), D-(ii).