Biology Test 268

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Biology Test 268

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Weekly Quiz Competition

Question 1
4 / -1

Uridine, present only in RNA is a

A
nucleoside

B
nucleotide

C
purine

D
pyrimidine

Solution

A nucleoside is pentose sugar and base together, without the phosphate group. Uracil is present as uridine in RNA only.

Uracil + Ribose Uridine
Question 2
4 / -1

The correct sequence of phases of cell cycle is

A

B

C

D
Question 3
4 / -1

During cell growth, DNA synthesis takes place on

A
S-phase

B

C

D
M phase

Solution

In S-phase (synthetic phase) of cell cycle, the chromosomes replicate. For this their DNA molecules function as templates and form carbon copies. The DNA content doubles i.e., 1C to 2C for haploid cells and 2C to 4C for diploid cells. As a result duplicate sets of genes are formed. Along with replication of DNA new chromatin fibres are formed which, however, remain attached in pairs and the number of chromosomes does not increase. As chromatin fibres are elongated chromosomes, each chromosome comes to have two chromatin threads or sister chromatids which remain attached at a common point called centromere.
Question 4
4 / -1

When cell has stalled DNA replication fork, which checkpoint should be predominantly activated?

A
G₁/S

B
G₂/M

C
M

D

Solution

If cell has stalled DNA replication fork, it implies that it has crossed CG1 or G1 cyclin cell cycle check point and has entered S-phase of cell cycle, where it is preparing for chromosome replication. Afterwards it will enter G2 phase and will soon approach second check point called mitotic cyclin (CM) which lies between G2 and M-phase.
Question 5
4 / -1

What will be the direction of flow of water when a plant cell is placed in a hypotonic solution?

A
Water will flow in both directions.

B
Water will flow out of the cell.

C
Water will flow into the cell.

D
No flow of water in any direction
Question 6
4 / -1

The water potential of pure water is

A
less than zero

B
more than zero but less than one

C
more than one

D
zero
Question 7
4 / -1

Two cells A and B are contiguous. Cell A has osmotic pressure 10 atm, turgor pressure 7 atm and diffusion pressure deficit 3 atm. Cell B has osmotic pressure 8 atm, turgor pressure 3 atm and diffusion pressure deficit 5 atm. The result will be

A
no movement of water

B
equilibrium between the two

C
movement of water from cell A to B

D
movement of water from cell B to A

Solution

Diffusion pressure deficit is the reduction in the diffusion pressure of water in a system over its pure state. It is given by DPD = O.P – W.P (T.P). DPD determines the direction of net movement of water. It is always from an area or cell of lower DPD to the area or cell of higher DPD. So, cell A having lower DPD, water will move from cell A to B.
Question 8
4 / -1

Which is essential for the growth of root tip?

A
Zn

B
Fe

C
Ca

D
Mn

Solution

Calcium (Ca) is necessary for the proper growth and functioning of root tips and meristems.
Question 9
4 / -1

In which of the following all three are macronutrients?

A
Molybdenum, magnesium, manganese

B
Nitrogen, nickel, phosphorus

C
Boron, zinc, manganese

D
None of these

Solution

Macronutrients are essential elements which are present in easily detectable quantities, 1-10 mg per gram of dry weight. The macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, potassium, calcium and magnesium. Micronutrients or trace elements, are needed in very small amounts (equal or less than 0.1 mg/gm of dry matter).
These include iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel.
Question 10
4 / -1

Oxygenic photosynthesis occurs in

A
Oscillatoria

B
Rhodospirillum

C
Chlorobium

D
Chromatium

Solution

Oscillatoria is a filamentous cyanobacteria which performs oxygenic photosynthesis because of the presence of chlorophyll-a like eukaryotic algae and higher plants.