Which of the following is an incorrect statement? [2021]
Nuclear pores act as passages for proteins and RNA molecules in both directions between nucleus and cytoplasm.
Mature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles.
Microbodies are present both in plant and animal cells.
The perinuclear space forms a barrier between the materials present inside the nucleus and that of the cytoplasm.
(2)
Sieve tube elements lack a nucleus at maturity and they are associated with companion cells for support.
Match List-I with List-II. [2021]
| List-I | List-II |
| (p) Cristae | (i) Primary constriction in chromosome |
| (q) Thylakoids | (ii) Disc-shaped sacs in Golgi apparatus |
| (r) Centromere | (iii) Infoldings in mitochondria |
| (s) Cisternae | (iv) Flattened membranous sacs in stroma of plastids |
Choose the correct answer from the options given below:
p-(ii), q-(iii), r-(iv), s-(i)
p-(iv), q-(iii), r-(ii), s-(i)
p-(i), q-(iv), r-(iii), s-(ii)
p-(iii), q-(iv), r-(i), s-(ii)
When the centromere is situated in the middle of two equal arms of chromosomes, the chromosome is referred as [2021]
acrocentric
metacentric
telocentric
sub-metacentric
(2)
Depending upon the position of the centromere, chromosomes are of four types:
(i) Acrocentric - Centromere is situated inner to telomere.
(ii) Metacentric - Centromere present in the middle of the chromosome.
(iii) Telocentric - Centromere terminal in the area of telomere.
(iv) Sub-metacentric - Centromere occurs slightly away from the middle of the chromosome.
The organelles that are included in the endomembrane system are [2021]
Golgi complex, endoplasmic reticulum, mitochondria, and lysosomes
Endoplasmic reticulum, mitochondria, ribosomes, and lysosomes
Endoplasmic reticulum, Golgi complex, lysosomes, and vacuoles
Golgi complex, mitochondria, ribosomes, and lysosomes
(3)
The endomembrane system includes endoplasmic reticulum (ER), Golgi complex, lysosomes, and vacuoles.
Which is the important site of formation of glycoproteins and glycolipids in eukaryotic cells? [2020]
Endoplasmic reticulum
Peroxisomes
Golgi bodies
Polysomes
(3)
The Golgi apparatus is the important site of formation of glycoproteins and glycolipids. Proteins synthesized by the rough endoplasmic reticulum and lipids synthesized by the smooth endoplasmic reticulum reach the cisternae of the Golgi apparatus. Here, they combine with carbohydrates to form glycoproteins and glycolipids.
Which of the following statements is not correct? [2019]
Lysosomes are formed by the process of packaging in the endoplasmic reticulum.
Lysosomes have numerous hydrolytic enzymes.
The hydrolytic enzymes of lysosomes are active under acidic pH.
Lysosomes are membrane-bound structures.
(1)
Lysosomes are single membrane-bound vesicles that contain hydrolytic enzymes. Lysosomes are believed to be formed by the joint activity of the ER and Golgi complex. Precursors of hydrolytic enzymes are synthesized at the RER and are transferred to the forming face of the Golgi complex. These precursors are then changed to enzymes. Enzymes are then packed in larger vesicles and are pinched off at the maturing face. These vesicles combine with endosomes to produce lysosomes. Lysosomal enzymes function in an acidic medium or pH 4.5. This pH is lower than that of the cytoplasm.
Which of the following statements regarding mitochondria is incorrect? [2019]
Mitochondrial matrix contains single circular DNA molecule and ribosomes.
Outer membrane is permeable to monomers of carbohydrates, fats, and proteins.
Enzymes of electron transport are embedded in the outer membrane.
Inner membrane is convoluted with infoldings.
(3)
Enzymes of electron transport are embedded in the inner membrane of mitochondria.
The shorter and longer arms of a submetacentric chromosome are referred to as [2019]
m-arm and n-arm respectively
s-arm and l-arm respectively
p-arm and q-arm respectively
q-arm and p-arm respectively
(3)
The short arm of a chromosome is termed as the p arm, and the longer arm is referred to as the q arm.
Which of the following pairs of organelles does not contain DNA? [2019]
Nuclear envelope and Mitochondria
Mitochondria and Lysosome
Chloroplast and Vacuoles
Lysosomes and Vacuoles
