Tag: senescence

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Questions Related to senescence

Multiple choice senescence senescence and death plant growth plant growth and development biology

Deciduous trees shows

  1. Progressive senescence

  2. Synchronous senescence

  3. Top senescence

  4. Whole senescence
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The simultaneous senescence which is also known as the synchronous senescence is the process in which the leaves of temperate deciduous tree undergo senescence and falls off in the late autumn season of the year. This type of senescence is controlled by the environmental factors. In this process only leaves fall off and root and shoot remain as it is.

So the correct answer is B.

Multiple choice senescence senescence and death plant growth plant growth and development biology

Progressive senescence occurs in

  1. Annual plants

  2. Perennial plants

  3. Biennial plants

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Senescence refers to a number of controlled processes which finally culminate in the death of the plant part. There are different forms of senescence which are observed in the plants during ageing. Progressive senescence is the form in which there is the gradual death of all the parts of the plant. The parts above the ground are affected first. This type of senescence is observed in the perennial plants.

Thus, the correct answer is option B. 

Multiple choice senescence senescence and death plant growth plant growth and development biology

Senescence and death are essential in the functioning of

  1. Sieve tubes

  2. Companion cells

  3. Both A and B

  4. Xylem and Sclerenchyma cells
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Senescence and death are essential to the functioning of xylem and sclerenchyma cells. Older organs when senesce and shed, their nutrient contents are withdrawn for nutrition of growing parts of the plant. Fallen leaves lead to release of mineral nutrients in soil for reuse by plants. 
So, the correct answer is 'Xylem and Sclerenchyma cells.'
Multiple choice senescence senescence and death plant growth plant growth and development biology

The fluidity of membranes in a plant in cold weather may be maintained by?

  1. Increasing the number of phospholipids with unsaturated hydrocarbon tails

  2. Increasing the proportion of integral proteins

  3. Increasing concentration of cholesterol in membrane

  4. Increasing the number of phospholipids with saturated hydrocarbon tail
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In cold weather, membranes tend to solidify. Increasing the proportion of unsaturated phospholipids (which have kinks in their tails) prevents tight packing, thereby maintaining fluidity.

Multiple choice senescence senescence and death plant growth plant growth and development biology

Senescense in plants leads into .......... of cells.

  1. Increase in size

  2. Increase in number

  3. Death

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

Senescence also known as aging refers to the decrease in the functional capacity of an organism. This results in a cellular breakdown followed by metabolic failure. The death of cells followed by the death of plant is seen in senescence. Thus the correct answer is option C.

Multiple choice senescence senescence and death plant growth plant growth and development biology

Senescence of detached leaves can be delayed by the use of.

  1. Auxin

  2. Giberellin

  3. Cytokinin

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

Cytokinins are plant hormones that promote cell division and are famously known for delaying leaf senescence and chlorophyll degradation in detached leaves. Auxins and gibberellins have different primary growth roles, while ethylene typically accelerates ripening and senescence.

Multiple choice senescence senescence and death plant growth plant growth and development biology

The induction of cell elongation by IAA is explained on the basis of ______________.

  1. The acid growth hypothesis

  2. Auxin-ethylene balance hypothesis

  3. Sodium-potassium pump hypothesis

  4. Osmotic pressure hypothesis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The acid growth hypothesis explains that auxin (IAA) stimulates proton pumps to acidify the cell wall, activating enzymes that loosen the wall and allow for cell elongation.

Multiple choice senescence senescence and death plant growth plant growth and development biology

Yellowing and shedding of leaves in autumn in many trees is an example of.

  1. Over all senescence

  2. Deciduous senescence

  3. Top senescence

  4. Progressive senescence
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The yellowing and shedding of leaves in autumn is a classic example of overall senescence, where the entire plant organ undergoes programmed aging and nutrient recycling.

Multiple choice senescence senescence and death plant growth plant growth and development biology

Senescence is?

  1. A process of shedding leaves

  2. An irreversible catabolic phase of the aging process

  3. A process of shedding flowers

  4. A reversible metabolic phase in the growth of the plant
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Senescence is defined as the programmed, irreversible catabolic phase of the aging process that leads to structural degradation and eventual death of a cell, organ, or organism. It is an internal, regulated phase rather than a reversible metabolic state.

Multiple choice senescence senescence and death plant growth plant growth and development biology

Which one of the following generally increases during senescence?

  1. Protein

  2. Chlorophyll

  3. Photosynthesis

  4. Respiration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During leaf senescence, cellular components are broken down, leading to a decrease in protein, chlorophyll, and photosynthetic activity. However, respiration often shows a temporary surge or remains active initially to supply energy for the mobilization of nutrients, meaning it generally increases relative to the declining metabolic baseline.