Cell the Unit of Life MCQs

Read the statements regarding chloroplast structure:

I. Mesophyll chloroplasts are lens-shaped, oval, spherical, discoid, or ribbon-like.
II. Number of chloroplasts varies from 1 per cell in Chlamydomonas to 20-40 per cell in mesophyll cells.
III. Thylakoids are arranged in stacks called grana present in the stroma.
IV. Stroma contains double-stranded circular DNA, 80S ribosomes, and starch-synthesizing enzymes.

Which of the above options is correct?

Consider the following statements regarding ribosomes:

I. First observed under electron microscope as dense particles by George Palade (1953).
II. Ribosomes are composed of RNA and proteins and are not surrounded by any membrane.
III. Eukaryotic ribosomes are 80S (composed of 60S and 40S subunits).
IV. S stands for Svedberg's unit, which directly measures density and mass.

Which of the statement combinations is correct?

Which statements regarding the cytoskeleton are correct?

I. Cytoskeleton consists of microtubules, microfilaments, and intermediate filaments.
II. Cytoskeletal structures are present only in prokaryotic cytoplasm.
III. They provide mechanical support and help in cell motility.
IV. They are involved in maintaining the shape of the cell.

Which statements are correct?

Consider the statements regarding cilia and flagella structure:

I. Cilia and flagella are hair-like outgrowths of the plasma membrane.
II. Axoneme possesses 9 doublets of peripheral microtubules and 2 central single microtubules (9+2 array).
III. Central tubules are connected by bridges and enclosed by a central sheath.
IV. Radial spokes connect the central sheath to one of the tubules of each peripheral doublet, totaling 9 spokes.

Which options are correct?

Read the following statements about centrosome and centrioles:

I. Centrosome contains two cylindrical structures called centrioles lying perpendicular to each other.
II. Centrioles show an organization like a cartwheel with 9 peripheral doublets of tubulin.
III. The central proteinaceous part of centriole is called hub, connected to peripheral triplets by radial spokes.
IV. Centrioles form the basal body of cilia/flagella and spindle apparatus during cell division in animal cells.

Which statements are correct?

Consider the statements regarding nuclear structure:

I. Nucleus was first described by Robert Brown in 1831.
II. Stained nuclear material was named chromatin by Flemming.
III. Perinuclear space (10-50 nm) separates the two parallel nuclear membranes.
IV. Outer nuclear membrane is continuous with ER and bears ribosomes.

Which combinations are correct?

Which of the following statements about nuclear pores and nucleolus are correct?

I. Nuclear pores are formed by fusion of two nuclear membranes.
II. Nuclear pores allow movement of RNA and proteins in both directions between nucleus and cytoplasm.
III. Nucleolus is a membrane-bound structure inside nucleoplasm.
IV. Nucleolus is the active site for ribosomal RNA (rRNA) synthesis.

Which statements are correct?

Consider the statements regarding human chromosomes and chromatin:

I. Chromatin contains DNA, basic proteins called histones, non-histone proteins, and RNA.
II. A single human cell has approximately 2-metre-long thread of DNA distributed among 46 chromosomes.
III. Primary constriction of a chromosome is called centromere.
IV. Disc-shaped structures present on the sides of centromere are called kinetochores.

Which options are correct?

Match the chromosome types based on centromere position with statements:

I. Metacentric chromosome has middle centromere forming two equal arms.
II. Sub-metacentric chromosome has centromere slightly away from middle, forming one shorter and one longer arm.
III. Acrocentric chromosome has centromere close to end forming one extremely short and one very long arm.
IV. Telocentric chromosome has centromere situated in the middle of equal arms.

Which statements are correct?

Which of the following statements about satellite chromosomes and microbodies are correct?

I. Satellite is a small fragment appearing due to non-staining secondary constriction at constant location.
II. Microbodies are membrane-bound minute vesicles containing various enzymes.
III. Microbodies are present only in plant cells and absent in animal cells.
IV. Mature mammalian erythrocytes and sieve tube cells lack a nucleus.

Which statements are correct?