Biology · Science General

Cell Biology and Structure

3,221 Questions

Cell biology focuses on the structure and function of cellular organelles. Key topics include cellular respiration, DNA inheritance, and energy production. These fundamental biology concepts are crucial for medical entrance and state service examinations.

Cell organelles functionsCellular respiration sitesDNA and ribosomesAnimal cell structurePlant cell components

Cell Biology and Structure Questions

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

In yeast mitochondria UGA codes for:

  1. Termination codon

  2. Initiation codon

  3. Tryptophan

  4. Tyrosine glycerate concentration
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In standard nuclear codes, UGA typically acts as a stop codon, but in yeast mitochondria it codes for the amino acid tryptophan. This represents a well-known deviation in the mitochondrial genetic code compared to the universal genetic code.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Which of the following organelles contain circular DNA.

  1. Peroxisomes and mitochondria

  2. Mitochondria and Glgicomplex

  3. Chloroplasts and Lysosomes

  4. Mitochondria and chloroplast
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Mitochondria and chloroplast are the organelles that show the presence of circular DNA.
The circular DNA in chloroplast is self-replicating and is known as cpDNA. It is involved in the synthesis of some intra-organelle proteins.
The mitochondrial circular DNA is self-replicating and is called mt DNA. It is also involved in the synthesis of some intra-organelle proteins.
Thus the correct answer is option D.
Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

How many organelles of a eukaryotic animal cell possess their own DNA?

  1. 1

  2. 2

  3. 3

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

Mitochondria and chloroplasts are the only two organelles of animal and plant cells that contain their own DNA. They not only contain their own DNA, but they also have their own ribosomes. These little protein-making machines are given information from the DNA to build certain proteins.

So, the correct option is '2'.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Mitochondria and chloroplasts are believed to be bacterial endosymbionts of cells because

  1. They have their own nucleic acids.

  2. Their membranes resemble those of cyanobacteria.

  3. They do arise de novo.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mitochondria and Chloroplasts are the only cell organelles other than nucleus coated with double membrane. They have their own DNA and protein synthesizing machinery as well. One explanation for a cell organelle to have its own DNA is that these organelles were separate organisms. The chloroplast was an autotrophic cyanobacteria and the mitochondria was a separate heterotrophic organism which later on became lodged into a eukaryotic cell as endosymbionts.

Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Extranuclear inheritance is a consequence of presence of genes in

  1. Lysosomes and ribosomes

  2. Mitochondria and chloroplasts

  3. Endoplasmic reticulum and mitochondria

  4. Ribosomes and chloroplast
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
DNA and RNA is the genetic material that carries information from one generation to another. Apart from this genetic material in the nucleus, the cytoplasm also contributes to the inheritance of some characters. Such characters are cytoplasmic inherited characters and this phenomenon is called as cytoplasmic inheritance. It is also called extra nuclear inheritance, because in this type of inheritance factors lies outside the nucleus of the cell. The cytoplasm contains various cell organelles including mitochondria, chloroplast are regarded as semi-autonomous as they contain their own genetic material-DNA. Hence cytoplasmic inheritance involves inheritance of mitochondrial DNA and/or chloroplast DNA.
So, the correct answer is 'Mitochondria and chloroplasts'.
Multiple choice component of the cell cell and cell organelles cell organelles cell: the unit of life biology cell as structural and functional unit basics of cell

Which of the following is an incorrect statement about the possible endosymbiotic origin of chloroplasts and mitochondria?

  1. They are of appropriate size to be descendants of bacteria

  2. They contain their own genome and produce all their own proteins

  3. They contain circular DNA molecules not associated with histones

  4. Their membranes have enzymes and transport systems that resemble those found in the plasma membranes of prokaryotes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The endosymbiotic theory states that mitochondria and chloroplasts were once free-living prokaryotes. While they have their own genome, they do not produce all their own proteins; many have been transferred to the host nucleus.

Multiple choice bio-chemistry organization of life concept of metabolism metabolism in animals metabolism

Which of the following life processes is evolved around RNA?

  1. Metabolism

  2. Translation

  3. Splicing

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

RNA plays a central role in various life processes, including the synthesis of proteins (translation), the processing of pre-mRNA (splicing), and various regulatory metabolic functions. Therefore, all listed processes involve RNA.

Multiple choice botany living world of animals number and shape of cells unicellular and multicellular organisms diversity and classification in animals cell parameters

Efficient large-sized cells are

  1. Elongated

  2. Elongated or branched

  3. With large surface area

  4. Having microvilli
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • Generally, cells are small so they can have an efficient surface area to volume ratio. Cells are so small so they can diffuse faster and all their processes will be a lot faster because of the smaller size of the cell.
  • For the large sized cells to become Efficient the cells must be elongated in order to have an efficient surface area to volume ratio.
  • Hence efficient large-sized cells are elongated.
  • So, the correct answer is 'Elongated'.

    • Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

    Which one is enucleated?

    1. Squamous epithelial cells

    2. Mature leucocyte of man

    3. Mature erythrocyte of frog

    4. Mature erythrocyte of man

    5. Osteocyte in man
    Reveal answer Fill a bubble to check yourself
    D Correct answer
    Explanation

    • Enucleation is the phenomenon in which the nucleus is removed. Enucleation occurs roughly when the cell has reached maturity.
    • Red blood cells or Erythrocytes are initially produced in the bone marrow with a nucleus. They then undergo a process known as enucleation.
    • Enucleation allows the red blood cell to contain more hemoglobin and therefore, carry more oxygen molecules. It also allows the cell to have its distinctive bi-concave shape which aids diffusion. This shape would not be possible if the cell had a nucleus in the way. Hence mature erythrocyte of man is enucleated.
    • So, the correct answer is 'Mature erythrocyte of man'.

    Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

    Growth at cellular level, is principally a consequence of increase in the amount of

    1. Protoplasm

    2. DNA

    3. Cell wall

    4. Cell organelles
    Reveal answer Fill a bubble to check yourself
    A Correct answer
    Explanation

    Protoplasm comprises of cytoplasm, nucleus and other cell organelles. Growth at cellular level includes increase in size of nucleus and other cell organelles. The growth at cellular level is a result of increase in amount of protoplasm.

    Thus, the correct answer is 'Protoplasm.'

    Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

    Refer to the following table for your possible answer.

    Cell types analysed Average mass of DNA/cell (x $10^{-11}$g)
    X $0.00$
    Y $3.35$
    Kidney $6.70$
    Lung $6.70$

    What is the correct identify of cell type X and Y?

    1. X-sperm cell, Y-liver cell

    2. X-liver cell, Y-smooth muscle cell

    3. X-smooth muscle cell, Y-mature red blood cell

    4. X-mature red blood cell, Y-sperm cell
    Reveal answer Fill a bubble to check yourself
    D Correct answer
    Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

    Smaller cells have

    1. Small surface area per volume ratio.

    2. Large surface area per volume ratio.

    3. Slow exchange rate of nutrients.

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

    Surface area to the volume ratio gets smaller as the cell gets larger. Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. Small cells, therefore, have a large surface area to volume ratio. The large surface area to volume ratio of small cells makes the transport of substances into and out of cells extremely efficient.

    Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

    Large cells have a

    1. High metabolic rate.

    2. High respiration rate.

    3. Low surface: volume ratio.

    4. High surface: volume ratio.
    Reveal answer Fill a bubble to check yourself
    C Correct answer
    Explanation

    As a cell increases in size, its volume increases much faster than its surface area. This results in a decrease in the surface area to volume ratio, which limits the efficiency of nutrient and waste exchange.

    Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

    When a cell of $2\mu$$m$ diameter grows to double its diameter, its surface area: volume relationship will _____________.

    1. Remain the same.

    2. Become double.

    3. Reduce to half.

    4. Become undetermined.
    Reveal answer Fill a bubble to check yourself
    C Correct answer
    Explanation

    Surface area (SA) is proportional to r^2 and volume (V) to r^3. The ratio SA/V is proportional to 1/r. If the diameter (and thus radius) doubles, the ratio becomes 1/2 of the original.