CUET UG Biology Booster Test 2-Agricultural Applications

The Green Revolution achieved high yields through a combination of better management practices, improved high-yielding varieties, and the application of agrochemicals (fertilizers and pesticides). Therefore, suggesting that the "total elimination of all chemical pesticides" was a reason for increased yields is factually incorrect and contradicts the very nature of the Green Revolution's agricultural model.

While agrochemicals successfully increased production, they are synthetic, costly, and can have long-term environmental consequences. For small-scale farmers in developing countries, the high recurring cost of these chemicals is a major barrier, creating a practical need for alternatives like GM crops (which can provide pest resistance naturally) and organic farming.

Statement I is inaccurate because while the food supply tripled, it did not "completely" satisfy global needs or solve hunger; population growth continued to outpace production. Statement II is correct; conventional breeding has reached a plateau where further significant increases in yield using only existing varieties are difficult or impossible, necessitating biotechnological intervention.

Conventional breeding relies on cross-hybridization, which is time-consuming and labor-intensive, often taking years to develop a single stable variety. As the global population surged, these methods failed to keep pace with food demand, creating the need for the rapid, high-throughput systems offered by micro-propagation and tissue culture.

The passage explicitly states: "the nutrient medium must provide a carbon source such as sucrose." Sucrose provides the energy required for the explant's metabolic processes during regeneration in a test tube.

Totipotency refers to the genetic and physiological capacity of a single somatic cell or explant to undergo division and differentiation to reconstruct the entire mature plant. It is the core concept underlying tissue culture.

Statement I correctly defines micro-propagation as a rapid, high-volume production method using tissue culture. Statement II is correct because commercial biotechnology has successfully used these methods for important food crops, including the ones listed.

In tissue culture, plants are regenerated from somatic cells (non-reproductive cells) through mitosis, which ensures that the offspring are exact genetic duplicates of the parent. Hence, the term "somaclone" (somatic + clone).

The correct logical sequence for meristem culture is: (2) Identify an infected plant, (1) Remove the apical/axillary meristem, (4) Grow that meristem in vitro, and finally (3) Obtain the virus-free, healthy plant.

The fundamental scientific basis for meristem culture is that viruses cannot move into the actively dividing, undifferentiated tissue of the apical or axillary meristems. Consequently, these regions remain virus-free even in a heavily infected plant, allowing for the recovery of healthy clones.

Matching based on NCERT definitions: (1 D) Explant is any tissue taken for in vitro growth; (2- A) Totipotency is the ability to generate a whole plant from a cell; (3- B) Somaclone refers to the identical offspring produced via micro-propagation; (4- C) Protoplast is the naked cell (plasma membrane only) remaining after wall digestion.

Somatic hybridisation allowed for the creation of the Pomato by fusing tomato and potato protoplasts. However, the resulting plant was a failure in practical agriculture because it did not successfully combine the desired traits of both parents (e.g., it lacked good tuber quality and good fruit quality), meaning Statement C is false.

The text provides a broad definition for GMOs: "Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO)."

(1 D) Pest resistance is synonymous with reduced pesticide reliance. (2- B) Mineral efficiency prevents soil fertility exhaustion. (3- C) Abiotic tolerance helps survive environmental stressors like cold and drought. (4- A) Tailor-made plants supply industrial resources like biofuels.

Genetic modification for mineral efficiency allows the plant to use existing soil nutrients more effectively. This preserves soil fertility for a longer duration. Therefore, "a rapid increase in the depletion of soil minerals" is the opposite of the intended and actual benefit of this technology.

One of the key applications of GM technology is increasing the shelf life of produce, which directly assists in reducing post-harvest losses. This keeps food fresher for longer during distribution, a major benefit for both farmers and consumers.

The progression of agricultural biotechnology, as presented in the chapter, moves from (1) the Green Revolution/Agrochemical phase, followed by (2) the development of tissue culture and micro-propagation, to (3) the modern implementation of Genetic Engineering (GM crops).

Golden Rice is a classic example of using genetic modification to enhance the nutritional profile of a major staple crop. It was specifically engineered to be Vitamin A-enriched to address widespread Vitamin A deficiency.

Tailor-made plants are designed to provide raw materials (starches, fuels, pharmaceuticals) for industry. They are not designed to produce "toxic agrochemicals for direct spray"—in fact, the goal of biotech is usually to reduce reliance on such chemicals.

The textbook specifically uses the term "tailor-made plants" for GM plants that have been engineered to supply alternative resources (like starches, fuels, or pharmaceuticals) to industrial sectors.