BIO 101 | Study Mode

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Question 101
A
chemiosmotic theory 
B
Munchs hypothesis (mass flow model) 
C
relay pump theory of Godlewski 
D
Cholodny-Wonts model. 
Explanation.
Share Answer Chemiosmotic coupling hypothesis is the most widely accepted explanation for oxidative phosphorylation in mitochondria and photophos- phorylation in thylakoid membranes. Mitchell proposed the idea of chemiosmotic coupling. <br /> He suggested that a concentration gradient of protons is established across the mitochondrial membrane because there is an accumulation of hydrogen ions on one side of the mitochondrial membrane. The proton accumulation is necessary for energy transfer to the endergonic ADP phosphorylation process.

Correct Option:
A
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Question 102
A
centriole 
B
spindle fibre 
C
cell plate 
D
centromere. 
Explanation.
Share Answer The centrioles occur in nearly all animal cells and in motile plant cells, such as zoospores of algae, sperm cells of ferns, and motile algae. They are absent is amoebae, prokaryotic cells, higher gymnosperms and all angiosperms. An interphase (undividing) cell has a pair of centrioles (diplosome) usually near the nucleus. <br /> They lie in a small mass of specialized, distinctly staining cytoplasm that lacks other cell organelles. The centrioles and the centrosphere are together referred to as centrosome. <br /> Before cell division, the centrioles duplicate so that a dividing cell has a pair of centrioles at each pole of the spindle. Spindle fibre, cell plate and centromere are present in all plant cells.

Correct Option:
A
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Question 103
A
centrosomes 
B
golgi bodies 
C
ribosomes 
D
mitochondria. 
Explanation.
Share Answer The ribosomes provide space for the synthesis of proteins in the cell. Hence, they are known as the protein factories of the cell. The ribosomes bound to the membranes generally synthesize proteins for export as secretions by exocytosis, or for incorporation into membranes, or for inclusion into lysosomes. <br /> The free ribosomes generally produce enzymic proteins for use in the cell itself.

Correct Option:
C
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Question 104
A
mitochondria 
B
spherosomes 
C
nucleus 
D
cell wall. 
Explanation.
Share Answer The spherosomes are, spherical bodies, about 0.5-1 nm wide and enclosed by a single unit membrane. <br /> They contain granular contents rich in lipids but also have some proteins. They occur in most plant cells but are abundant in the endosperm cells of oil seeds. Spherosomes, arise from the endoplasmic reticulum.

Correct Option:
B
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Question 105
A
ribosome 
B
peroxisome 
C
endoplasmic reticulum 
D
mitochondria. 
Explanation.
Share Answer Glycolysation of protein means linking of sugars to proteins which starts in rough endoplasmic reticulum and completed in golgi complex.

Correct Option:
C
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Question 106
A
poleward movement 
B
to initiate the RNA synthesis 
C
to seal the ends of chromosome 
D
to recognise the homologous chromosome. 
Explanation.
Share Answer Inside the cell nucleus, all our genetic information is located on twisted, double stranded molecules of DNA which are packaged into chromosomes. At the end of these chromosomes are telomeres, zones of repeated chains of DNA. <br /> The telomere is like a cellular clock, because every time a cell divides, the telomere shortens. After a cell has grown and divided a few dozen times, the telomeres turn on an alarm system that prevents further division. <br /> The DNA in the chromosome acts like a sort of instruction manual for the cell. Genetic information is transcribed into segments of RNA that then go out into the cell and carries out a variety of tasks. It was thought that telomeres were silent that their DNA was not transcribed into strands of RNA. The researchers have turned this theory on its head by discovering telomeric RNA and showing that this RNA is transcribed from DNA on the telomere.

Correct Option:
A
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Question 107
A
ribosomes which occur on nuclear membrane and E.R. 
B
ribosomes of only cytosol 
C
ribosomes of only nucleolus and cytosol 
D
ribosomes of only mitochondria and cytosol. 
Explanation.
Share Answer Ribosomes present in nuclear membrane and endoplasmic reticulum take part in protein synthesis. Two or more ribosomes simultaneously engaged in protein synthesis on the same mRNA strand forming polyribosomes. The ribosome functions as a template, bringing together different components required for protein synthesis.

Correct Option:
A
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Question 108
A
osmotic pressure 
B
suction pressure 
C
turgor pressure 
D
wall pressure. 
Explanation.
Share Answer The pressure required to stop the flow of pure water into a solution across a semi permeable membrane is a characteristic of the solution, and is called the osmotic pressure. Thus water will move from a region of low osmotic pressure to a region of high osmotic pressure. Turgor pressure is the hydrostatic pressure set up within a cell by the water present acting against the elasticity of the wall Suction pressure when referred to a cell, is the force which is available for taking in water.

Correct Option:
A
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Question 109
A
oxidative enzymes 
B
hydrolytic enzymes 
C
reductive enzymes 
D
anabolic enzymes. 
Explanation.
Share Answer A lysosome is a tiny sac bounded by a single unit membrane of lipoprotein. It contains a dense, finely granular fluid. The latter consists of glycoprotein hydrolytic (digestive) enzymes called acid hydrolases. These include proteases, lipases, nucleases, glycosidases, sulphatases, acid phosphatases, etc. <br /> However, all the enzymes do not occur in the same lysosome. There are different sets of enzymes in different lysosomes. The lysosome enzymes can break down all major biological macromolecules present in the cells or entering the cells from outside into their building block subunits by addition of water. The lysosome enzymes are active in acid medium, at about pH 5, hence their name.

Correct Option:
B
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Question 110
A
phytochrome 
B
chlorophyll 
C
anthocyanin 
D
carotenoids. 
Explanation.
Share Answer Phytochrome is a plant pigment that can detect the presence or absence of light and is involved in regulating many processes that are linked to day length (photoperiod), such as seed germination and initiation of flowering. <br /> It consists of a light-detecting portion, called a chromophore, linked to a small protein and exists in two intercovertible forms with different physical properties, particularly in the ability to bind to membranes. Chlorophyll occurs in all land plants and is responsible for their green colour. Chlorophyll molecules are the principal sites of light absorption in the light-dependent reactions of photosynthesis. <br /> Anthocyanin occurs in the cell vacuoles of various plant organs and is responsible for many of the blue, red and purple colours in plants. <br /> Carotenoids are responsible for the characteristic colour of many plant organs, such as ripe tomatoes, carrots, and autumn leaves. They also occur in certain algae and other photosynthesizing organisms (such as phototrophic bacteria), in which they function as accessory pigments in the light-dependent reaction of photosynthesis.

Correct Option:
A
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