Tag: plant growth

Questions Related to plant growth

The terminal phase of ageing is called as

senescence senescence and death plant growth plant growth and development biology

  1. Dedifferentiation

  2. Senescence

  3. Abscission

  4. None of the above

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Correct Option: B
Explanation:

Ageing is the result of a sequential switching on and off of certain genes. Ageing results in senescence. Senescence refers to a number of controlled processes which finally culminate in the death of the plant part. The senescence is considered as the last phase in the process of ageing. 

Thus, the correct answer is option B. 

During senescence of a plant.

senescence senescence and death plant growth plant growth and development biology

  1. The plant displays sequential senescence of the leave

  2. Metabolites like carbohydrates, proteins etc. Are transported from young leaves to the aging leaves

  3. Metabolites like carbohydrates, proteins etc. Are transported out of the aging leaves to the young leaves

  4. Secondary plant products accumulate in the tissues are organs during aging

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Correct Option: A

Senescent phase of an organism's life span can be recognised by

senescence senescence and death plant growth plant growth and development biology

  1. Slow metabolism

  2. Cessation of reproduction

  3. Decreased immunity

  4. All of the above

Show answer
Correct Option: D
Explanation:
The terminal irreversible stage of ageing is called senesence. This is the last phase of life span, that ultimately leads to death. This phase can be recognised by slow metabolism, cessation of reproduction and decreased immunity.

So, the correct answer is 'All of the above'.

When a plant undergoes senescence, the nutrients may be ____________.

senescence senescence and death plant growth plant growth and development biology

  1. Accumulated

  2. Bound to cell wall

  3. Translocated

  4. None of these

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Correct Option: C
Explanation:

When a plant part undergoes senescence, nutrient resources(minerals and carbohydrates) shift away or are translocated from the senescened part to other parts. In leaves at the time of senescene we observe loss of chlorophyll, RNA and protein, transport of nutrients and then abscission.

Senescence in plants leads into .......... of cells.

senescence senescence and death plant growth plant growth and development biology

  1. Increase in size

  2. Increase in number

  3. Death

  4. Differentiation

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Correct Option: C
Explanation:

Senescence in plants is a process of aging. During process of senescence, cells undergo differentiation. It ultimately leads into the death of cells. 

Thus, the correct answer is option C.

Fastest phase of S-shaped growth curve is

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. Lag phase

  2. Log Phase

  3. Stationary phase

  4. Both (a) and (B).

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Correct Option: B
Explanation:

  • S-shaped logistic growth curve includes 3 phases:
  • Lag phase - When some organisms are introduced in an area, the population growth begins slowly.
  • Log phase - The conditions are ideal and the maximum growth rate is reached.
  • Stationary phase - Growth rate begins to slow down as factors such as food, water and space become limiting.
Thus, the correct answer is 'Log phase.'

Most realistic growth curve is

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. J-shaped

  2. Sigmoid

  3. Parabolic

  4. Both (A) & (B)

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Correct Option: B
Explanation:

The resources for the growth of most animal population are finite and become limiting sooner or later, thus the logistic growth model is considered more realistic. The equation for model gives a sigmoid shaped graph when plotted against the N in relation to time.  The equation is :

dN/dT=rN(K-N/K) 
where, 
N is Population density at time t
r is the intrinsic rate of natural increase 
K is carrying capacity.
So, the correct answer to the question is 'Sigmoid'.

What is wrong w.r.t annual rings ?

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. These are also called growth ring

  2. One annual ring includes one circle of spring wood and one circle of autumn wood

  3. Annual rings are distinct in plants of tropical regions

  4. they give an estimate of the age of tree

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Correct Option: A

Most realistic growth curve 

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. J shaped

  2. Sigmoid

  3. Parabolic

  4. Bith A and B

Show answer
Correct Option: B
Explanation:
The resources for the growth of most animal population are finite and become limiting sooner or later, thus the logistic growth model is considered more realistic. The equation for model gives a sigmoid shaped graph when plotted against the N in relation to time.  
The equation is :
$\dfrac{dN}{dT}$ = $rN$ $\dfrac{(K-N)}{K}$ 
where, 
N is Population density at time t
r is the intrinsic rate of natural increase 
K is carrying capacity.
So, the correct answer to the question is 'Sigmoid'.

Fastest phase of S-shaped growth curve is?

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. Lag phase

  2. Log phase

  3. Stationary phase

  4. Both $(1)$ and $(2)$

Show answer
Correct Option: A