Following are certain statements related to plants exposed to dehydration stress:

A. When the water potential of the rhizosphere decreases due to water deficit, plants can continue to absorb water as long as plant water potential is lower than that of soil water.

B. The ratio of root to shoot growth increases in response to water deficit.

C. Plant cells tend to release solutes to lower water potential during periods of osmotic stress.

D. Abscisic acid is synthesized at a higher rate when leaves are dehydrated, and more ABA accumulates in the leaf apoplast.

Which one of the following combinations of above statements is correct?

• A, B and C

• B, C and D

• A, B and D

• A, C and D

Which of the following options match the plant tissue type with its correct function in vascular plants?

Tissue	Function
A. Tracheids	(i) Chief water-conducting element in gymnosperms
B. Vessel elements	(ii) Chief water-conducting element in angiosperms
C. Sieve tube element	(iii) Food-conducting element in gymnosperms
D. Sieve cell	(iv) Food-conducting element in angiosperms

• A - (i); B - (ii); C - (iv); D - (iii)

• A - (ii); B - (i); C - (iii); D - (iv)

• A - (i); B - (ii); C - (iii); D - (iv)

• A - (i); B - (iii); C - (iv); D - (ii)

The following genes have been genetically engineered to develop herbicide resistance in plants:

A. Resistance to glyphosate using the 5-enolpyruvyl shikimate-3-phosphate synthase gene.

B. Bialaphos resistance using the bar gene.

C. Sulfonyl urea resistance using the acetolactate synthase gene.

D. Atrazine resistance using the glutathione S-transferase gene.

In which of the above two case the mechanism is based on abolition of herbicide binding to the enzyme?

• A and D

• B and C

• C and D

• A and C

Ethylene is an important plant hormone that regulated several aspects of plant growth and development. Some statements are given below in relation to ethylene signalling pathways:

A. Unbound ethylene receptors work as positive regulators of the response pathway.

B. There are more than two ethylene receptors known to date.

C. The carboxy-terminal half of the ethylene receptor, ETR1 (Ethylene-response 1), contains a domain homologous to histidine kinase catalytic domain.

D. EIN2 (Ethylene-insensitive 2) encodes a transmembrane protein. The ein2 mutation promotes ethylene responses in both the seedlings and adult Arabidopsis plants.

Which combination of the above statements is correct?

• A and B

• B and C

• C and D

• D and A

105.

Examples of many factors that regulate plant height in response to gibberellic acid (GA) are listed below:

A. Binding of a GA-bound repressor to the promoter of the DELLA domain-containing GRAS protein gene and blocking its expression.

B. Binding of the GA-receptor complex to GRAS.

C. Directing GRAS for ubiquitination and degradation by the 26S proteasome.

D. Micro RNA directed down-regulation of the GRAS protein expression.

Which of the following combinations is correct?

• A and B

• B and C

• C and D

• A and D

Many factors related to the role of abscisic acid (ABA) in contributing to drought, cold, and salt response in plants are listed below:

A. The transcription factors DREB1 and DREB2 bind to the cis-acting elements of the promoter of ABA-responsive genes in an ABA-dependent manner.

B. ABA induces many genes such as LEA and RED29.

C. ABA-responsive genes contain six-nucleotide ABRE elements of the promoter.

D. Nine-nucleotide dehydration-responsive elements DRE are present in ABA-responsive genes.

Which one of the following combinations of the above statements is correct with respect to ABA?

• A, B, and C

• A, C, and D

• B, C, and D

• A only

Following are certain statements regarding CO₂ assimilation in higher plants:

A. The action of aldolase enzyme during Calvin-Benson produces fructose 1,6-bisphosphate.

B. The conversion of glycine to serine takes place in mitochondria during C₂ oxidative photosynthetic  carbon cycle.

C. During C₄ carbon cycle, NAD-malic enzyme releases the CO₂ from the 4-carbon acid, malate yielding a 3-carbon acid, pyruvate.

D. Malic acid during crassulacean acid metabolism (CAM) is stored in mitochondria during dark and released back to cytosol during day.

Which one of the following combinations of above statements is correct?

• A, B, and C

• A, C, and D

• B, C, and D

• A, B, and D

Following are certain statements regarding terpene class of secondary metanolites in plants:

A. Isopentenyl diphosphate and its isomer combine to form larger terpenes.

B. Diterpenes are 20 carbon compounds.

C. All terpenes are derived from the union of 4-carbon elements.

D. Pyrethroids are monoterpene esters.

Which one of the following combination of above statements is correct?

• A, B, and C

• A, B, and D

• B, C, and D

• A, C, and D

Gibberellic acid (GA) controls seed germination by directing the breakdown of the stored starch. In which one of the following tissues of the barley seed, α-amylase gene is induced in response to GA?

• Endosperm

• Coleoptile

• Aleurone layer

• Embryo

For which one of the following physiological studies ¹²CO₂ and ¹³CO₂ are used?

• Estimate the rate of photosynthesis

• Determine rate of photorespiration

• The ratio of C₄ and CAM pathways of CO₂ fixation

• The ratio of C₃ and C₄ pathways of CO₂ fixation.