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 bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Which of the following cell organelles in concerned with photophosphorylation?

  1. Mitochondria

  2. Plastochondria

  3. Chloroplast

  4. More than one option is concerned
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The synthesis of ATP is called phosphorylation. If it occurs in the presence of light, it is called photophosphorylation, that occurs during photosynthesis in the chloroplast. Mitochondria perform oxidative and substrate level phosphorylation.

Hence, the correct answer is 'Chloroplast'

Multiple choice zoology tissue level of organisation muscle tissue structure of protein muscle tissues

Which of the following is an incorrect match of cell junction along with its structure and function?

  1. Cell junction - Tight junctions,
    Structure - Tightly bound, leak proof, fibrous protein 'belt' that surrounds cells ,
    Functions - Organizing junction : hold cells together such that material passes through but not between the cells.

  2. Cell junction - Desmosomes
    Structure - Intermediate filaments linked to adjoining cells through cadherins cytoskeleton.
    Functions - Anchoring junction : "buttons" cells together.

  3. Cell junction - Plasmodesmata
    Structure - Six transmembrane connexon proteins creating a "pipe" that connects cells
    Function - Communicating junctions : allow passage of small molecules from cell to cell in a tissue.

  4. Cell junction - Adherens junctions
    Structure - Transmembrane fibrous proteins.
    Functions - Anchoring junction : "roots" extra-cellular matrix to cytoskeleton.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plasmodesmata are channels that traverse the cell walls of plant cells and some algal cells, allowing transport and communication between them. They are not made of connexon proteins; connexons are found in gap junctions in animal cells.

Multiple choice biology multicellular structure: tissue muscle tissue structure of protein muscle tissues

Sarcosome is a term used for

  1. Mitochondria

  2. Golgi bodies

  3. Ribosomes

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

Since the 1850s cytologists observed some granular structures in the cytoplasm of the living cells. These structures were originally named as sarcomas. The term mitochondrion was introduced by Carl Benda in 1898. The term mitochondrion became the widely used name for this organelle but still the term sarcosome is accepted to denote this organelle present in the muscle. Sarcosome is a large specialized mitochondrion found in a striated muscle fiber.
Thus, the correct answer is the option (A), 'Mitochondria'.

Multiple choice biology multicellular structure: tissue muscle tissue structure of protein muscle tissues

High contents of myoglobin and cytochromes are present in

  1. Red muscles

  2. White muscles

  3. Intermediate muscles

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

Red muscle gives a fused contraction at a slower frequency of stimulation. The red color of muscles is due partly to myoglobin, which is probably freely dissolved in the sarcoplasm and partly to the cytochrome, which are mainly associated with the particulate components of the cytoplasm.
Thus, the correct answer is option (A), 'Red muscles'.

Multiple choice biology animal tissue muscle tissue structure of protein muscle tissues

In heart cells, which one serves as a second messenger, speeding up muscle cell contraction in response to adrenaline _____________.

  1. cAMP

  2. cGMP

  3. GTP

  4. ATP

  5. AMP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In cardiac muscle cells, adrenaline binds to beta-adrenergic receptors, activating adenylate cyclase to produce cAMP, which acts as a second messenger to increase contraction rate and force.

Multiple choice zoology tissue level of organisation muscle tissue structure of protein muscle tissues

A human cell which contains a large amount of RER, many golgi bodies and a prominent nucleolus is most likely a

  1. Muscle cell

  2. Secretory cell

  3. Nerve cell

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

A cell with abundant rough endoplasmic reticulum, numerous golgi bodies, and a prominent nucleolus is heavily involved in protein synthesis and secretion, making it a secretory cell.

Multiple choice expression of gene inherited changes biology

Which is correct

  1. Both animal and plant cells have a well defined cell wall

  2. Cells are formed de novo from abiotic materials

  3. Cells of all living organisms have a nucleus

  4. In prokaryotes there are no membrane bound cell organelles.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Prokaryotic cells lack membrane-bound organelles like the nucleus, mitochondria, or chloroplasts, which is a defining characteristic distinguishing them from eukaryotic cells.

Multiple choice zoology immunity phagocytosis cells in immune system immune system, its cells, mediators and antigens

In which of the following organelle the MHC II molecule gets assembled before exogenous antigen processing?

  1. Lysosomes

  2. Endoplasmic reticulum

  3. Vacuoles

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
In the endoplasmic reticulum, during synthesis of class II MHC, the α and β chains are produced and complexed with a special polypeptide called invariant chain. The nascent MHC class II protein has its peptide-binding cleft blocked by the invariant chain to prevent it from binding cellular peptides or peptides from the endogenous pathway. The chain also aids the export of class II MHC from the Endoplasmic reticulum to the Golgi, followed by fusion with a late endosome containing endocytosed, degraded proteins. Thus the correct answer is option B.
Multiple choice zoology immunity phagocytosis cells in immune system immune system, its cells, mediators and antigens

During endogenous antigen processing, the antigens are cleaved in which of the following organelle?

  1. Endoplasmic reticulum

  2. Proteosomes

  3. Golgi bodies

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

The endogenous pathway is used to present cellular peptide fragments broken down by proteosomes on the cell surface of MHC class I molecules. Transporter associated with antigen processing spans the membrane of the rough endoplasmic reticulum and transports the peptides into the lumen of the rough endoplasmic reticulum. Once the peptide is transported into the ER lumen it binds to the cleft of the MHC class I molecule, stabilizing it and allowing it to be transported to the cell surface by the Golgi apparatus. Thus the correct answer is option B.

Multiple choice zoology immunity phagocytosis cells in immune system immune system, its cells, mediators and antigens

Anaplasia  is

  1. Transfer of cancer cells

  2. Formation of tumour

  3. Loss of cell adeherence and cell differentioation

  4. Action of lysosomes over cells
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Anaplasia is a condition of cells with poor cellular differentiation, losing the morphological characteristics of mature cells and their orientation with respect to each other and to endothelial cells. Such loss of structural differentiation is especially seen in most, but not all, malignant neoplasms. Hence, Anaplasia is the loss of adherence and cell differentiation.

So, the correct answer is 'Loss of cell adherence and cell differentiation'.

Multiple choice biology movement in and out of the cell transport of molecules osmosis and plasmolysis plant water relation

Decreasing order concentration of minerals inside cell is

  1. Ca$^{+2}$$-$K$^+$$-$Na$^+$.
  2. K$^+$$-$Ca$^{+2}$$-$Na$^+$.
  3. K$^+$$-$Na$^+$$-$Ca$^{+2}$.
  4. Na$^+$$-$K$^+$$-$Ca$^{+2}$.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Potassium ions are usually higher inside the cell than outside the cell, and its concentration inside the cell is about 10 to 30 fold higher than the other components, while sodium ion is higher outside the cell than inside the cell. 
So, the answer is C.