Tag: number and shape of cells

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Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

The maximum work that a standard Daniell cell can do before it stops working is
$[1 \,F = 96487\, C\, mol^{-1}\, and\, E^o = 1.1 V]$

  1. $212.271\, kJ \,mol^{-1}$
  2. $21.227\, kJ \,mol^{-1}$
  3. $721.221 \,kJ \,mol^{-1}$
  4. $71.222 \,kJ \,mol^{-1}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The maximum work (Gibbs free energy change) is calculated as W = nFE. For a Daniell cell, n=2. W = 2 * 96487 * 1.1 = 212271.4 J/mol, which is 212.271 kJ/mol.

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

The surface area to volume ratio increase as the cell size 

  1. Unaltered

  2. Slightly increase

  3. Decrease

  4. Increase in many layers
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The total area on the surface of an object is called as 'Surface area' and here the object is 'cell'. While the volume is the amount of the space present inside the cell.

The volume is expressed in cubic units while surface area is expressed in square units
The surface area and volume gets affected, when size of the cell is altered i.e., either increased or decreased.
Let's see how the surface area and volume ratio gets affected...

  • When the cell size increases, the volume increases more than surface area because the volume increases in cubes while surface area increases in squares. Hence, both volume and surface area increases at different rates. And here the surface area to volume ratio decreases as the volume is more than surface area.
  • When the cell size decreases, the volume decreases at unequal rates with respect to surface area. This leads to an increase of the surface area to volume ratio.
Therefore, the surface area to volume ratio increases with the decrease in cell size.

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

Smaller cells have

  1. Small surface area per volume ratio.

  2. Large surface area per volume ratio.

  3. Slow exchange rate of nutrients.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Surface area to the volume ratio gets smaller as the cell gets larger. Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. Small cells, therefore, have a large surface area to volume ratio. The large surface area to volume ratio of small cells makes the transport of substances into and out of cells extremely efficient.

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

Large cells have a

  1. High metabolic rate.

  2. High respiration rate.

  3. Low surface: volume ratio.

  4. High surface: volume ratio.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As a cell increases in size, its volume increases much faster than its surface area. This results in a decrease in the surface area to volume ratio, which limits the efficiency of nutrient and waste exchange.

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

When a cell of $2\mu$$m$ diameter grows to double its diameter, its surface area: volume relationship will _____________.

  1. Remain the same.

  2. Become double.

  3. Reduce to half.

  4. Become undetermined.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Surface area (SA) is proportional to r^2 and volume (V) to r^3. The ratio SA/V is proportional to 1/r. If the diameter (and thus radius) doubles, the ratio becomes 1/2 of the original.

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

Metabolically active cells have

  1. Lower nucleocytoplasmic ratio.

  2. Higher nucleocytoplasmic ratio.

  3. Higher surface: volume ratio.

  4. Both B and C.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Metabolically active cells require efficient exchange (high surface area to volume ratio) and often have a large nucleus to manage cellular processes (higher nucleocytoplasmic ratio).

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

Volumes of prokaryotic and eukaryotic cells are ........... respectively.

  1. $0.2-10\mu {m}^{3}$ and $1000-10000\mu {m}^{3}$
  2. $0.1-10\mu {m}^{3}$ and $100-1000\mu {m}^{3}$
  3. $0.1-5.0\mu {m}^{3}$ and $3-30\mu {m}^{3}$
  4. $0.1-1.0\mu {m}^{3}$ and $10-100\mu {m}^{3}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Prokaryotic cells are generally much smaller, typically in the range of 0.2 to 10 cubic micrometers, while eukaryotic cells are significantly larger, ranging from 1000 to 10000 cubic micrometers.

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

A bacterium divides every 35 minutes . If a culture containing $ 10^5$ cell per ml is grown for 175 minutes. What will be the cell concentration per ml after 175 mts _______________.

  1. $32 \times 10^5$ cells
  2. $5 \times 10^5$ cells
  3. $35 \times 10^5$ cells
  4. $175 \times 10^5$ cells
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
It is given that a bacterium divides every 35 minutes,
At 0 minutes, the culture contains $ 10^5 $ cells/ml.
After 35 minutes, the culture will contain $ 2^1 \times 10^5 $ cells / ml
similarly, after 175 minutes, that is after 5 generations, the no. of cells
$ = 2^{5} \times 10^{5}$ cells/ml.
This is equal to $ 32 \times 10^{5} $ cell/ml
So, (A) is the correct answer.
Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

Read the given statements and select the correct option.


(i) One maize root cell can give rise to more than 17,500 cells.
(ii) A cell in watermelon can increase in size upto 3,50,000 times.
(iii) The growth of pollen tube is measured in terms of length.
(iv) The growth of the leaf is measured in term of surface area.

  1. Statements (i) and (ii) are correct.

  2. Statements (iii) and (iv) are correct.

  3. Statements (i) and (iii) are correct.

  4. Statements (i), (ii), (iii) and (iv) are correct.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The root cells may give rise to more than 17,500 cells, the cells of the root undergo mitotic division in an arithmatic manner, where some of the dividing cells undergo differentiation while others continue to divide.

A water melon pulp contains about 90% of water, so the enormous increase in size of the cell is due to endosmosis.
The growth of the pollen tube is measures in $\mu$ meters
A leaf visually is a two dimensional structure hence it is measured in terms of surface area.
So, the correct answer is 'Statements (i), (ii), (iii) and (iv) are correct.'

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

The average volume of a eukaryotic cell is

  1. Between 1 $\mu \, m^3$ and 1,000 $\mu \, m^3$
  2. Between 100 $\mu \, m^3$ and 1,000 $\mu \, m^3$
  3. Between 10 $\mu \, m^3$ and 100 $\mu \, m^3$
  4. Generally greater than 10,000 $\mu \, m^3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A cell of 1 μm^3 volume average to the maximum 1,000 μm^3 most highly expressed proteins in a cell.

So, the correct option is 'Between 1 μm^3 and 1,000 μm^3'.