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

Which of the following observations most strongly supports the view that mitochondrial membranes have Electron Transport System (ETS) enzymes?

  1. Mitochondria have a property to concentrate in the locomotive cells.

  2. Mitochondria have a folded inner membrane structure.

  3. Disruption of mitochondrial membrane yields out fragments that are able to synthesise ATP.

  4. A contractile protein capable of utilising ATP is obtained from mitochondria.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If fragments of the mitochondrial membranes are able to synthesise ATP, it is proved that the ATP synthesising enzymes are localised in the inter-membranous space. ATP synthesis is achieved only by the path of Electron Transport Chain, so the enzymes involved in the chain are bound to be located in there.

Multiple choice

“Intussusception” is a well-known physical property of primary cell wall. It is characterised as

  1. hardening of cell wall

  2. deposition of cell wall material from outside as layers

  3. deposition of cell wall material from inside to cause growth

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Intussusception is the the expansion of the cell wall in plants as a result of the introduction of new molecules of cellulose and protopectin into the already formed wall. Instussusception is a well-known term as a medical condition of instestines where a part of the intestine has invaginated into another section of intestine, similar to the way in which the parts of a collapsible telescope slide into one another.

Multiple choice

Animal Cell and Plant Cells differ in their cytology is a well-known fact. The following two questions need to be answered based on the clarity of the cell doctrine and cellular function.

Who suggested the cytological difference between a plant cell and an animal cell?

  1. Schleiden: Plant cells have cell wall.

  2. Schleiden and Schwann: The cell theory suggests the difference.

  3. Schwann: Animal cells do not have a cell wall.

  4. Virchow: Plant cells have cell wall.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

It was Mathias Schwann who brought out the difference between the plant cell and animal cell based on the microscopic observation of plant cells provided by Schleiden. Schwann, Schleiden and Virchow are the three contributors of The Cell Theory. Schleiden was a botanist and did not observe animal cells. Virchow contributed with his famous doctrine of “omnis cellula e cellula- Cells originate from existing cells”. Schwann experimented both with animal as well as plant cells and marked the difference as “Animal cells do not have a cell wall”. The division cycle of both the animal and plant cells proceeds through same cycles, except for the cytokinesis where plant cells have a special structure formed known as cell plate, which will later become the cell wall.

Multiple choice

Cell membranes are dynamic structures constituted of various biochemical entities. Many models have been proposed for defining the structure and constitution of membranes. The most accepted of these is the Singer and Nicholsons’ fluid mosaic model. Based on the knowledge of Singer and Nicholsons’ model, answer the following:

Which of the following statements justifies the correct biochemistry profile of the plasma membrane with respect to individual constituents?

  1. Lipids are in the least proportion, while carbohydrates and proteins are slightly higher but in equal proportions.

  2. Proteins are in the least proportion, while carbohydrates are slightly higher and lipids are the most abundant of all.

  3. All the three are in equal proportions.

  4. Carbohydrates are in the least proportion, while proteins are slightly higher and lipids are the most abundant of all.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fluid mosaic model proposed that plasma membrane comprises of a phospholipid bilayer with extrinsic and intrinsic proteins embedded into it along with protein channels. Apart from these, glycolipids and glycoproteins, though present minutely, form the antennae-like structures to assist in recognition and identification.  

Multiple choice

Plasma membranes are the interface of the cell. Therefore, they have some specialised components that take care of the recognition and identification. The recognition responsibility of the plasma membrane lies with

  1. protein portion of glycoproteins

  2. carbohydrate portion of glycoproteins

  3. Both protein and carbohydrate portions of glycoproteins

  4. Sphingosine region of sphingolipids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbohydrates are the sole biochemical structures which are employed for recognition or identification purpose in biological systems, be it Lectins for adhesions or blood group typing. The whole field of glycobiology deals with carbohydrates and their properties.

Multiple choice

In regular molecular laboratory procedures, “Binding Membranes” are used for blotting assays. The analogy of such membranes in an animal cell is

  1. unit membrane

  2. biological membrane

  3. plasma membrane

  4. cell coat
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Binding Membranes are uniform, paper thin, white plastic supports, having specially designed porous structure and binding sites suitable for transfer and hybridisation of biological molecules. Plasma membranes amongst the given options suits the best characteristics of binding membranes, especially the selective permeability and holding capacity.

Multiple choice

There exist varied membrane systems in the cellular systems, but one unique system is the “Endomembrane System” in which there exists a contiguous plasma membrane. Which of the following pair of organelles in the endomembrane system shares their membranes?

  1. Endoplasmic reticulum and Golgi apparatus

  2. Nucleus and Endoplasmic reticulum

  3. Nuclear pore and Ribosomes

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

In the entire membrane system, endomembrane system comprises of organellar transport from nucleus to vesicles and finally to plasma membrane wherein the cell membranes of the nucleus and adjacent Rough ER are contiguous and ER contributes more than half percent of the total plasma membrane of the cell.

Multiple choice

Which of the following statements is false?

  1. Each chloroplast is surrounded by a double membrane envelop.

  2. Chlorenchyma cells of leaves contain 20-40 chloroplasts.

  3. In many algae, chloroplast is the largest cell organelle.

  4. Chloroplasts were discovered by Briedenbach in 1883.

  5. Chromoplasts have various shapes due to the crystallisation of carotenoids.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

False. Chloroplasts were not discovered by Briedenbach in 1883. It is discovered by Schimper in 1883. So, this option is right.