21.

The smooth endoplasmic reticulum is the major site for synthesis of

• Protein

• Lipid

• Glycoproteins

• Carbohydrates

• Carbohydrates

Which of these is wrongly matched?

• 70 S ribosomes — Prokaryotes

• 80 S ribosomes — Eukaryotes

• Axoneme — Cilia

• Centromere — Centrosome

• Centromere — Centrosome

In a polypeptide, amino acids are linked by

• An ester bond

• A hydrogen bond

• A covalent bond

• A glycosidic bond

• A glycosidic bond

Which of the following is/are cellulosic?

(i) Paper

(ii) Cotton fibre

(iii) Chitin

(iv) Glycogen

• (i) and (ii) only

• (i) and (iii) only

• (i), (iii) and (iv) only

• (iii) and (iv) only

• (iii) and (iv) only

Which of the following statements about amino acids is false?

• Based on the nature of the carboxyl group there are many amino acids

• Amino acids are substituted methane

• Amino acids have an amino group and acidic group as substituent on the $\mathrm{\alpha }$-carbon

• There are four substituent groups occupying the four valency positions

• There are four substituent groups occupying the four valency positions

Which of the following phases correspond to the interval between mitosis and initiation of DNA replication?

• S phase

• G₁ phase

• G₂ phase

• M phase

• M phase

Which of these is not a key feature of meiosis?

• Meiosis involves two sequential cycles of nuclear and cell division 

• Meiosis involves pairing of homologous chromosomes

• Two cycles of DNA replication occur during meiosis

• Three is recombination between the paired homologous chromosomes

• Three is recombination between the paired homologous chromosomes

When a molecule moves across a membrane independent of other molecules the process is called

(i) Uniport

(ii) Symport

(iii) Antiport

• (i) only

• (i) and (ii) only

• (i) and (iii) only

• (ii) and (iii) only

• (ii) and (iii) only

Apopalstic movement of water occurs exclusively through the

(i) Intercelluar spaces

(ii) Walls of the cells

(iii) Plasmodesmata

(iv) Cytoplasm

• (i), (ii) and (iv) only

• (iii) and (iv) only

• (i) and (ii) only

• (ii) and (iv) only

• (ii) and (iv) only

Which of the following is not a role played by potassium in plant growth?

• Translocation of carbohydrates

• Maintaining anion-cation balance

• Opening and closing of stomata

• Synthesis of protein

• Synthesis of protein