Plant Physiology
- A few drops of sap were collected by cutting across a plant stem by a suitable method. The sap was tested chemically. Which one of the following test results indicates that it is phloem sap? Answer: 1. Alkaline Phloem sap is rich in sugar (mainly sucrose), has a high refractive index because of dissolved solutes, and is alkaline... 1
- Which is essential for the growth of root tip? Answer: 2. Ca Calcium is needed for the formation of the middle lamella (calcium pectate) of the cell wall and for the spindle during cell d... 1
- You are given a tissue with its potential for differentiation in an artificial culture. Which of the following pairs of hormones would you add to the medium to secure shoots as well as roots? Answer: 1. Auxin and cytokinin In tissue culture, the ratio of auxin to cytokinin controls differentiation. A balanced supply gives both roo... 1
- Phytochrome is a Answer: 3. chromoprotein Phytochrome is a pigment protein with a light-absorbing non-protein part (a linear tetrapyrrole, phytochromobilin)... 1
- Water vapour comes out from the plant leaf through the stomatal opening. Through the same stomatal opening carbon dioxide diffuses into the plant during photosynthesis. Reason out the above statements using one of following options : Answer: 2. Both processes can happen together because the diffusion coefficient of water and CO ₂ is different. Both processes can occur tog... 1
- A plant in your garden avoids photorespiratory losses, has improved water use efficiency, shows high rates of photosynthesis at high temperatures and has improved efficiency of nitrogen utilisation. In which of the following physiological groups woul… Answer: 2. C ₄ The listed features are the hallmarks of C₄ plants. C₄ plants have Kranz anatomy and PEP carboxylase, which fixes CO₂ in meso... 1
- The *Avena* curvature is used for bioassay of : Answer: 3. IAA Key idea: The Avena (oat coleoptile) curvature test is a bioassay for the auxin IAA. Auxin placed on one side of a decapitate... 1
- Emerson's enhancement effect and Red drop have been instrumental in the discovery of : Answer: 2. Two photosystems operating simultaneously Key idea: Red drop and Emerson's enhancement effect showed that two light reactions wor... 1
- In a chloroplast the highest number of protons are found in : Answer: 2. Lumen of thylakoids Key idea: During the light reactions, protons build up inside the thylakoid lumen. They come from water split... 1
- In which of the following, all three are macronutrients ? Answer: Dropped in the official answer key: full marks to every candidate Key idea: Macronutrients are C, H, O, N, P, S, K, Ca and Mg. Micro... 1