1. What are those structures that appear as ‘beads-on-string’ in the chromosomes when viewed under an electron microscope?
 a) Nucleotides
 b) Nucleosomes
 c) Base pairs
 d) Genes

2. The two polynucleotide chains in DNA are
 a) Parallel
 b) Discontinuous
 c) Antiparallel
 d) Semi-conservative

3. Centrosome is not present in
 a) Cell of higher plants
 b) Cell of lower plants
 c) Cell of higher animals
 d) Cell of lower animals

4. Channel proteins are involved in
 a) Transport of enzymes
 b) Water transport
 c) Active transport of ions
 d) Passive transport of ions

5. Part of chromosome after secondary constriction is called
 a) Centriole
 b) Centromere
 c) Chromomere
 d) Satellite

6. Tubulin protein occurs in
 a) Digestive enzymes
 b) Rough endoplasmic reticulum
 c) Thylakoids
 d) Microtubules

7. Quantasomes are found in
 a) Mitochondria
 b) Chloroplast
 c) Lysosome
 d) Endoplasmic reticulum

8. In which one of the following would you expect to find glyoxysomes?
 a) Endosperm of wheat
 b) Endosperm of castor
 c) Palisade cells in leaf
 d) Root hairs

9. The non-membranous organelles are
 a) Centrioles
 b) Ribosomes
 c) Nucleolus
 d) All of these

10. Single stranded DNA is found in
 a) Polio viruses
 b) Rich dwarf virus
 c) TMV
 d) ϕ ×174

11. Ribosomes that occur exclusively in mitochondria is
 a) 70 S
 b) 55 S
 c) 30 S
 d) 50 S

12. Number of protofilament in microtubule is
 a) 13
 b) 12
 c) 5
 d) 10

13. …A… are granular structures first observed under electron microscope as dense particles by …B… (1953). Here, A and B refer to
 a) A-Ribosomes; B-Perner
 b) A-Lysosomes; B-de Duve
 c) A-Peroxisomes; B-Flemming
 d) A-Ribosomes; B-George Palade

14. Middle lamella is present
 a) Inside the secondary wall
 b) Inside the primary wall
 c) Outside the primary wall
 d) In between secondary and tertiary walls

15. Rough endoplasmic reticulum differs from smooth walled endoplasmic reticulum due to the presence of
 a) DNA
 b) Nucleus
 c) Ribosomes
 d) Ergastic substance

16. A widely accepted, improved model of cell membrane is
 a) Fluid mosaic model
 b) Robertson’s model
 c) Danielli and Davson’s model
 d) Unit membrane model

17. Organelle important in spindle formation during nuclear division is
 a) Golgi body
 b) Chloroplast
 c) Centriole
 d) Mitochondrion

18. Identify A to F in the sectional view of a chloroplast showing the different parts

 a) A-Inner membrane, B-Granum, C-Outer membrane, D-Stroma lamella, E-Stroma, F-Thylakoid
 b) A-Outer membrane, B-Inner membrane, C-Granum, D-Thylakoid, E-Stroma lamella, F-Stroma
 c) A-Thylakoid, B-Outer membrane, C-Stroma, D-Stroma lamella, E-Granum, F-Inner membrane
 d) A-Outer membrane, B-Stroma, C-Inner membrane, D-Granum, E-Thylakoid, F-Stroma lamella

19. Consider the following statements and choose the correct one
 a) Plant cells have centrioles which are absent in almost all animal cells
 b) Ribosomes are the site of protein synthesis
 c) The middle lamella is layer mainly of calcium carbonate which holds the different neighbouring cells together
 d) In animal cells, steroidal hormones are synthesised by smooth endoplasmic reticulum

20. The backbone of RNA consists of which of the following sugar?
 a) Deoxyribose
 b) Ribose
 c) Sucrose
 d) Maltose

1-b; 2-c; 3-a; 4-d 5-d; 6-d; 7-b; 8-b 9-d; 10-d; 11-b; 12-a 13-d; 14-c; 15-c; 16-a 17-c; 18-b; 19-b; 20-b

1 (b)
Nucleosome is sub-microscopic sub-unit of chromatin which is formed by wrapping of DNA over a core of histone proteins. The term was coined by Oudetet.al.., (1975). It is oblate structure with a length of 10nm and a thickness of 5-5.7nm. Its core is called nu-body. The latter is formed of four pairs of histone molecules H₂, A, H₂B, H₃ and H₄. DNA makes 1.75 turns over the octamer to form a nucleosome. Two adjacent nucleosomes are connected by a short segment of unboud DNA called linker DNA. A fifth type of histone called H₁ is attached over the linker DNA. Nucleosomes appear as ‘beads-on-string’ in the chromosomes under electron microscope.  

2 (c)
In 1953, James Watson and Francis Crick suggested that in a DNA molecule there are two polynucleotide chains arranged antiparallel or in opposite directions.

3 (a)
Centrosome is an organelle containing two cylindrical structures called centrioles and occurs in most algal cells (except red algae) and most animal cells. They are absent in prokaryotes, red algae, yeast, gymnosperms and angiosperms and some non-flagellated or non-ciliated protozoans.

4 (d)
There are two major classes of membrane transport proteins carrier proteins and channel proteins. Carrier proteins involved with active as well as passive transport of ions or solutes while channel proteins are involved only with passive transport.

5 (d)
Normally, the primary constriction is known as kinetochore. In some cases, chromosome contains non-staining secondary constriction called satellite

6 (d)
The ciliary microtubules are made up of tubulin. The two subfibres A and B are composed of α and β tubulin having mol. Wt. 56,000 and 58,000 respectively.

7 (b)
On the inner side of the thylakoid membranes of chloroplasts are present a paracrystalline array of particles (20×10 nm); these were called quantosomes by Park and Pon (1963).

8 (b)
Glyoxysomes were reported from the endosperm of germinating seeds, rich in fatty acids, by Beevers (1969). They serve as enzymatic site for reactions including the conversion of stored fatty acids to carbohydrate. Therefore, glyoxysomes will be present in endosperm of castor but not in endosperm of wheat, which is carbohydrate rich.

9 (d)
Nucleolus, ribosomes and centrioles are non-membranous cell organelles.

10 (d)
Single stranded DNA virus: Bacteriophageϕ×174, coliphage S 13, bacteriophage M13.

11 (b)
Besides DNA, a mitochondrion has RNA and its ribosomes also. Thus, a complete protein synthesising machinery is present in mitochondria. The ribosomes of mitochondria are small, i.e., 55-60 S type, with a large subunit of 40 S and a small subunit of 30 S. The large subunit contain 16-17 S and 5S rRNA and the small subunit 12-13 S rRNA.

12 (a)
Microtubules are electron microscopic structures found only in the eukaryotic cellular structures like cilia, flagella, centriole, etc. The wall of microtubule is 50Å thick, which is formed of 13 parallel prototubules.

13 (d)
Ribosomes are granular structures, first observed under electron microscope as dense particles by George Palade (1953)

14 (c)
Middle lamella is a thin binding layer between the cell wall of adjacent plant cells. It is chemically formed of pectates of calcium and magnesium. It is present towards the outside of primary wall.

15 (c)
Rough Endoplasmic Reticulum (RER) differs from Smooth Endoplasmic Reticulum (SER) due to the presence of ribosomes. Some other differences are as follows:

16 (a)
A widely accepted, improved model of the cell membrane is a fluid mosaic model

17 (c)
The centrioles appear as two cylindrical structures. They are formed of microtubules. In higher animals, they form the mitotic pole, ie, they are involved in the formation of spindles.

18 (b)
A-Outer membrane, B-Inner membrane, C-Granum, D-Thylakoid, E-Stroma lamella and F-Stroma

19 (b)
Ribosomes are the site of protein synthesis, also called protein factories. In the testes, ovary, and adrenal cortex, SER has a role in the synthesis of steroid hormones.

20 (b)
The backbone of RNA is made up of ribose sugar (5-carbon), whereas DNA consists of deoxyribose sugar. 

For any question, querries or suggestions, comment below.