Test: Cell: The Unit of Life - 1 - NEET MCQ

The shapes of bacteria are bacillus (rod like), coccus (spherical), vibrio (comma shaped) and spirillum (spiral).

Line in NCERT: "The four basic shapes of bacteria are bacillus (rod like), coccus (spherical), vibrio (comma shaped) and spirillum (spiral)."

 'The cytoskeleton in a cell is involved in functions like mechanical support, motility, and maintenance of the shape of the cell. It is not involved in the production of ATP, which is primarily a function of mitochondria.'

Topic in NCERT: CYTOSKELETON AND ITS FUNCTIONS

Line in NCERT: "The cytoskeleton in a cell are involved in many functions such as mechanical support, motility, maintenance of the shape of the cell."

Evaluating each statement for accuracy:

Statement A: This is correct. The lipid component of the plasma membrane does primarily consist of phosphoglycerides.
Statement B: This is incorrect. Polar molecules generally cannot pass through the lipid bilayer easily due to their polarity and typically require carrier proteins or channels to facilitate their transport.
Statement C: This is incorrect. The secondary cell wall is rigid and provides structural integrity; it does not grow once laid down and is formed on the inner side of the primary cell wall.
Statement D: This is correct. The quasi-fluid nature of lipids in the plasma membrane does allow for the lateral movement of proteins within the membrane.
Statement E: This is correct. The middle lamella, rich in pectins, acts like a glue that holds neighboring plant cells together.
Thus, two statements (B and C) are incorrect. Hence, the correct answer is Option D: Two.

Topic in NCERT: Cell Membrane

Line in NCERT: "As the polar molecules cannot pass through the nonpolar lipid bilayer, they require a carrier protein of the membrane to facilitate their transport across the membrane.
The middle lamella is a layer mainly of calcium pectate which holds or glues the different neighbouring cells together. The cell wall and middle lamellae may be traversed by plasmodesmata which connect the cytoplasm of neighbouring cells.
According to this, the quasi-fluid nature of lipid enables lateral movement of proteins within the overall bilayer. This ability to move within the membrane is measured as its fluidity."

Anton Von Leeuwenhoek first saw and described a live cell.

Line in NCERT: "Anton Von Leeuwenhoek first saw and described a live cell."

Mitochondria contain cristae, finger like projection of inner layer, thylakoid is present in chloroplast and lysosome is a digestive enzyme but RNA is absent in Chromosome.

Leucoplasts are involved in storing oils and fats, carbohydrates (starch), and proteins in plant cells. They can differentiate into various types depending on what they store: amyloplasts (storing starch), elaioplasts (storing oils), and proteinoplasts (storing proteins).

Topic in NCERT: Plastids

Line in NCERT: "The leucoplasts are the colourless plastids of varied shapes and sizes with stored nutrients: Amyloplasts store carbohydrates (starch), e.g., potato; elaioplasts store oils and fats whereas the aleuroplasts store proteins."

Mitochondria are the sites of aerobic respiration. They producecellular energy in the form of ATP

Line in NCERT: "Mitochondria are the sites of aerobic respiration. They produce cellular energy in the form of ATP, hence they are called 'power houses' of the cell."

In plant cells, the chloroplasts are responsible for trapping light energy essential for photosynthesis. The grana, in the plastid, is the site of light reactions.

Line in NCERT: "The grana, in the plastid, is the site of light reactions and the stroma of dark reactions."

Lysosomes are single membrane structures containing enzymes for digestion of all types of macromolecules.
Topic in NCERT: Lysosomes
Line in NCERT: These are membrane bound vesicular structures formed by the process of packaging in the golgi apparatus.

The cytoskeleton of a cell is made up of microtubules, actin filaments,and intermediate filaments. These structures give the cell its shape and help organize the cell’s parts. They also provide a basis for movement and cell division

Topic in NCERT: Cytoskeleton

Line in NCERT: An elaborate network of filamentous proteinaceous structures consisting of microtubules, microfilaments and intermediate filaments present in the cytoplasm is collectively referred to as the cytoskeleton.

Golgi apparatus is the important site of formation of glycoproteins and glycolipids.

Line in NCERT: "Golgi apparatus is the important site of formation of glycoproteins and glycolipids."

Mitochondria are present in both plant as well as animal cells. Plastids and central vacuoles are present in plant cells and centrioles are present in only animal cells.

Line in NCERT: "Mitochondria divide by fission."

Cilia present in prokaryotic organisms consist of microtubules. These microtubules are arranged in 9+2 order in which 2 forms the center and 9 are arranged at periphery.

Line in NCERT: "The axoneme usually has nine doublets of radially arranged peripheral microtubules, and a pair of centrally located microtubules. Such an arrangement of axonemal microtubules is referred to as the 9+2 array."

Given Diagram Annotations:

• A likely represents the outer membrane of the mitochondrion.
• B appears to represent the inner membrane, which is folded into cristae.
• C is probably pointing to the matrix, the area enclosed by the inner membrane.
• D could be the intermembrane space, the area between the inner and outer membranes.
• E seems to indicate a crista, which is a fold of the inner membrane into the matrix.

Evaluation of the Statements:

A: "C' possesses DNA molecule, RNA molecule and 80 S ribosomes"

• This statement is incorrect because while the matrix (labeled as 'C' here) does contain DNA and RNA, the ribosomes in mitochondria are 70S, not the 80S ribosomes found in the cytoplasm of eukaryotic cells.

B: "'A' and 'B' have their own specific enzymes"

• This statement is correct. 'A' (outer membrane) and 'B' (inner membrane) indeed have their own specific enzymes. The outer membrane contains enzymes like porins and others involved in transport functions. The inner membrane contains enzymes crucial for ATP synthesis, such as those in the electron transport chain and ATP synthase.

C: "'E' made by inner membrane towards the intermembrane space"

• This statement is incorrect. 'E' is a crista, which is not made towards the intermembrane space but extends into the matrix. It is a fold of the inner membrane increasing the surface area for mitochondrial functions like the electron transport chain.

D: "'B' forms the continuous limiting boundary of the organelle"

• This statement is incorrect. 'B', which indicates the inner membrane, does not form the continuous outer boundary. That role belongs to 'A', the outer membrane of the mitochondrion.

Based on the clarification and review of mitochondrial structure, the correct answer is still B: "'A' and 'B' have their own specific enzymes." This option accurately reflects the distinct roles and enzyme compositions of the outer and inner mitochondrial membranes.

4

A cell membrane shows fluid behavior due to mosaic of lipid and proteins. Fluid mosaic model of plasma membrane is most accepted and recent model.

Line in NCERT: "According to this, the quasi-fluid nature of lipid enables lateral movement of proteins within the overall bilayer."

The staining procedure developed by Gram viz., those that take up the gram stain are gram positiveand the others that do not are called gram negative bacteria.

Line in NCERT: "by Gram viz., those that take up the gram stain are Gram positive and the others that do not are called Gram negative bacteria."

• A. Thylakoids are described as flat membranous sacs, but specifically, they are located within the chloroplasts, not the Golgi apparatus. The correct match here would be (iii) Flat membranous sacs in stroma, which more accurately describes the location of thylakoids in the chloroplast stroma.

• B. Cristae are the infoldings in mitochondria, where the mitochondrial membrane is folded inward to increase the surface area. Therefore, the correct match is (iv) Infolding in mitochondria.

• C. Cisternae are flat membranous sacs found in the Golgi apparatus. Thus, the correct description is (i) Disc-shaped sacs in Golgi apparatus.

• D. Chromatin refers to the material of which chromosomes are composed, including DNA and proteins. It represents the condensed structure of DNA, so it matches with (ii) Condensed structure of DNA.

• A with iii
• B with iv
• C with i
• D with ii

The correct sequence for the pathway of a secretory product typically follows these steps:

Synthesis in the Rough Endoplasmic Reticulum (RER) - Proteins are synthesized and undergo initial modifications.
Transport via Vesicles - Proteins are packed into vesicles that bud off from the RER.
Cis Face of the Golgi Apparatus (GB) - Vesicles fuse with the cis face of the Golgi body, where further modification of proteins occurs.
Transit Through Golgi Apparatus - Proteins move from the cis to the trans region of the Golgi, undergoing further modifications.
Vesicles to Plasma Membrane - Finished proteins are packaged into vesicles that bud off from the trans face of the Golgi and are transported to the plasma membrane.
Therefore, Option A accurately describes the typical secretory pathway, starting from the Endoplasmic Reticulum (ER), moving through the Golgi body from the cis to the trans region, and finally to the plasma membrane.

Topic in NCERT: Golgi apparatus

Line in NCERT: "Materials to be packaged in the form of vesicles from the ER fuse with the cis face of the golgi apparatus and move towards the maturing face."

The correct order from smallest to largest is virus, PPLO (Mycoplasma), typical bacteria, and typical eukaryotic cell. Viruses are the smallest, usually only visible with an electron microscope. PPLOs are slightly larger than the largest viruses but smaller than typical bacteria. Typical bacteria are larger than viruses and PPLOs and are visible under light microscopes. Eukaryotic cells are the largest, significantly bigger than viruses, PPLOs, and typical bacteria, making Option A the correct choice.

Topic in NCERT: PROKARYOTIC CELLS

Line in NCERT: "Typical bacteria (1-2 µm) PPLO (about 0.1 µm) A typical eukaryotic cell (10-20 µm) Viruses (0.02-0.2 µm)"

Rudolf Virchow(1855) first explained that cells divided and new cells are formed .

Line in NCERT: "Rudolf Virchow (1855) first explained that cells divided and new cells are formed from pre-existing cells (Omnis cellula-e cellula)."

The leucoplasts are the colourless plastids of varied shapes and sizes with stored nutrients. Leucoplast includes: a) Amyloplasts storing carbohydrates. b) Elaioplastsstoring oils and fats and c) Aleuroplasts storing proteins.

Line in NCERT: "the leucoplasts are the colourless plastids of varied shapes and sizes with stored nutrients: Amyloplasts store carbohydrates (starch), e.g., potato; elaioplasts store oils and fats"

Mitochondria are double membranous structure. The inner membrane of mitochondria thrown into folds to form finger-like structureis called cristae.

Line in NCERT: "The inner membrane forms a number of infoldings called the cristae (sing.: crista) towards the matrix."

Reserve material in prokaryotic cells are stored in the cytoplasm in the form of inclusion bodies.

Line in NCERT: "Inclusion bodies: Reserve material in prokaryotic cells are stored in the cytoplasm in the form of inclusion bodies."

The centromere is essential for the proper segregation of chromosomes during cell division, as it holds the two sister chromatids together until they are separated.

Statement 1 is correct as it accurately describes the structure of the nuclear envelope and the perinuclear space. Statement 2 is incorrect because nuclear pores are found on both the inner and outer membranes of the nuclear envelope and facilitate the bidirectional movement of both RNA and protein molecules between the nucleus and cytoplasm. Thus, the only correct statement is 1.