​Given below are characteristic traits found in sun- or shade-acclimated leaves:

A. High dry mass per unit area

B. Higher number of chloroplasts per area

C. Lower Chl-a/Chl-b ratio

D. Lower dark respiration per area

E. Higher light harvesting complexes per area

Select the option that has all correct characteristics for shade-acclimated leaves:

Correct option is B

Shade-acclimated leaves (also called shade leaves) have distinct physiological and morphological traits that help them maximize light absorption in low-light conditions. These adaptations differ from sun-acclimated leaves (sun leaves), which are designed to tolerate higher light intensity.

Characteristics of Shade-Acclimated Leaves:

1. Lower Chl-a/Chl-b ratio (C)

   • Shade leaves have more chlorophyll-b than sun leaves.
   • Chlorophyll-b helps in capturing low-intensity light, leading to a lower Chl-a/Chl-b ratio compared to sun leaves.

2. Lower dark respiration per area (D)

   • Shade leaves have lower metabolic rates and reduced respiration rates per unit area, helping them conserve energy.

3. Higher light-harvesting complexes per area (E)

   • To efficiently capture low light, shade leaves contain more light-harvesting complexes (LHCs) associated with Photosystem II.

 Incorrect options:

• (A) High dry mass per unit area – Incorrect

  • Sun leaves have thicker mesophyll layers and higher leaf dry mass per unit area due to increased structural investments.
  • Shade leaves are thinner and have lower dry mass.

• (B) Higher number of chloroplasts per area – Incorrect

  • Sun leaves typically have more chloroplasts per unit area due to higher cell density and multiple layers of palisade tissue.
  • Shade leaves have larger but fewer chloroplasts.