Tag: biology

Quizzes (1160) Questions (12174)

Questions Related to biology

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

Which part of the cell controls one or more functions of the cell? 

  1. Nucleus

  2. Mitochondria

  3. Cell wall

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The nucleus is the most important part of the cell which regulates all the cellular activities by controlling the enzymes required for cellular processes. Enzymes are proteins and protein synthesis is controlled by nucleus as mRNA required for protein synthesis is made from DNA which is situated in the nucleus. 
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Which part of the cell helps the transfer of material from the nucleus to the cytoplasm?

  1. Nuclear pores

  2. Chromatin fibres

  3. DNA

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA is a long polynucleotide strand, coiled to make chromatin fibres to fit into the cell. It also helps to prevent DNA damage. It is situated in the nucleus. 

In eukaryotic cells, the nucleus is bound by a double membrane envelope. This envelope of the nucleus is called as nuclear envelope. It possesses openings at certain intervals called as 'nuclear pore'. Nuclear pores are large protein complexes molecule in the nuclear envelope. It is involved in regulation and transfer of material from nucleus and cytoplasm. Thus, the correct answer is option A.

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

What are the three major functional regions of a cell?

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

A nucleus is absent in the mature

  1. Sieve tube cells.

  2. Mammalian erythrocytes.

  3. Monocytes.

  4. Both A and B.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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

  1. Endoplasmic reticulum

  2. Nucleus

  3. Polyribosome

  4. Microtubule
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

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

How many membranes comprise the nuclear envelope?

  1. One

  2. Two

  3. Three

  4. None
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

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

The nucleus is not important as the site of:

  1. DNA synthesis

  2. RNA synthesis

  3. Synthesis of ribosomal subunits

  4. Protein synthesis
Reveal answer Fill a bubble to check yourself
D Correct answer
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'.

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

Which of these is not found in the nucleus?

  1. Nucleoplasm instead of cytoplasm

  2. Functioning ribosomes

  3. Chromatin that condenses to chromosomes

  4. Nucleolus that produces rRNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ribosomes are synthesized in the nucleolus but function in the cytoplasm. Therefore, functioning ribosomes are not found within the nucleus.

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

Acetabularia used in Hammerling's nucleocytoplasmic experiments is

  1. Unicellular fungus

  2. Multicellular fungus

  3. Unicellular uninucleate green alga

  4. Unicellular multinucleate green alga
Reveal answer Fill a bubble to check yourself
C Correct answer
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'.