121.

The genome of a bacterium is composed of a single DNA molecule which is 10⁹ bp long. How many moles of genomic DNA is present in the bacterium? [Consider Avogadro No = 6 × 10²³]

•  × 10^-23

•  × 10^-14

• 6 × 10¹⁴

• 6 × 10^-23

Coupling of the reaction centers of oxidative phosphorylation is achieved by which one of the following?

• Making a complex of all four reaction centers.

• Locating all four complexes in the inner membrane.

• Ubiquinones and cytochrome C.

• Pumping of protons

Enzymes accelerate a reaction by which one of the following strategies?

• Decreasing energy required to form the transition state.

• Increasing kinetic energy of the substrate.

• Increasing the free energy difference between the substrate and the product.

• Increasing the turn over number of enzymes.

A cell line deficient in the salvage pathway for nucleotide biosynthesis was fed with medium containing ¹⁵N labeled amino acids. Purines were then extracted. Treatment with which one of the following amino acids is likely to produce ¹⁵N labelled purines?

• Aspartic acid

• Glycine

• Glutamine

• Aspartamine

The ionic strength of a 0.2 M Na₂HPO₄ solution will be

• 0.2 M

• 0.4 M

• 0.6 M

• 0.8 M

A film projector and microscope give equal magnification. But a film projector is not used to see living cells because

• a living cell cannot be placed in a film projector.

• the viewer's eye is close to a microscope whereas it is far away from the projector's screen.

• a microscope produces a virtual image whereas a projector produces a real image.

• a microscope has greater resolving power than a projector.

Four circles of unit radius each are drawn such that each one touches two others and their centres lie on the vertices of a square. The area of the region enclosed between the circles is

• $\mathrm{\pi }$ - 1

• $\mathrm{\pi }$ - 2

• 3 - $\mathrm{\pi }$

• 4 - $\mathrm{\pi }$

A turtle swimming from a point A located on the circumference of a circular pond. After swimming for 4 meters in a straight line it hits pond. From there it changes direction and swims for 3 meters in a straight line and arrives at point D diametrically opposite to point A. How far is point D from A?

• 3m

• 4 m

• 7 m

• 5 m

Density of a rice grain is 1.5 g/cc and bulk density of rice heap is 0.80 g/cc. If a 1 litre container is completely filled with rice, what will be the approximate volume  of pore space in the container?

• 350 cc

• 465 cc

• 550 cc

• 665 cc

A living cell has a protoplasm which is water based and demarcated by a lipid bilayer membrane. If a cell is pierced up to 5^th of its diameter with a very sharp needle, after taking the needle out

• no effect will be observed.

• protoplasm will leak out from the hole made by the needle for a few minutes until the cell heals the wound.

• protoplasm will keep on leaking out till the cell is dead.

• the cell will burst like a balloon.