Grass leaves curl inwards during very dry weather. Select the most appropriate reason from the following :
1. Tyloses in vessels
2. Closure of stomata
3. Flaccidity of bulliform cells
4. Shrinkage of air spaces in spongy mesophyll
1. | A - Adaxial epidermis | 2. | B - Phloem |
3. | C - Mesophyll | 4. | D - Abaxial epidermis |
Identify the incorrect comparison between monocots and dicots in general:
Character | Monocots | Dicots | |
1. | Leaves | Parallel venation | Reticulate venation |
2. | Roots | Primary root of short duration, replaced by adventitial roots forming fibrous or fleshy root systems | Develops from the radicle. Primary root often persists forming strong tap roots and secondary roots |
3. | Plant stem: Vascular bundles | Ring of primary bundles with cambium, differentiated into cortex and stele | Numerous scattered bundles in ground parenchyma, cambium mostly absent, no differentiation between cortical and stelar regions |
4. | Flowers | Parts in threes (trimerous) or multiples of three | Fours (tetramerous) or fives (pentamerous) |
Regarding the guard cells:
1. | walls away from the stomatal pores are thin and those towards the stomatal pores are thick |
2. | walls away from the stomatal pores are thick and those towards the stomatal pores are thin |
3. | chloroplasts are mostly absent |
4. | play no role in the regulation of opening and closing of stomata |
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