Biotechnology

Statement 1 is Correct: Recombinant DNA technology allows for the movement of genes across different plant species to introduce desirable traits, such as transferring genes from wild grass species to cultivated wheat to improve disease resistance.

Statement 2 is Correct: Genes can be transferred from animals to plants. A well-known research example involves transferring antifreeze protein genes from cold-water fish (like the winter flounder) into plants like tomatoes and strawberries to enhance their frost tolerance.

Statement 3 is Correct: Genes from microorganisms are routinely transferred to higher organisms (plants and animals). For example, genes from the soil bacterium *Bacillus thuringiensis* (Bt) are transferred into crops like cotton and corn to provide resistance against lepidopteran pests.

Aflatoxins are poisonous carcinogens that are produced by certain moulds (Aspergillus flavus and Aspergillus parasiticus), which grow in soil, decaying vegetation, hay, and grain.

Statement 1 is correct: Mycorrhizae: - Greatly increase the effective root surface area - Improve water absorption - Help plants withstand drought stress

Statement 2 is correct: Mycorrhizal fungi help plants: - Grow in acidic or alkaline soils - Access nutrients even when pH reduces their availability

Statement 3 is correct: Mycorrhizae offer bioprotection: - Compete with soil pathogens - Produce antibiotics - Strengthen plant immune responses

Fruits remain biologically active even after harvesting. They continue to undergo respiration, a metabolic process in which stored sugars are broken down to release energy. This respiration accelerates ripening and eventual spoilage.

Cold storage works primarily by lowering temperature, which slows down enzymatic and metabolic processes inside the fruit. As temperature decreases, the rate of respiration decreases, delaying ripening and reducing microbial activity. This significantly increases the storage life of fruits.

Root hairs are extremely delicate, thin-walled outgrowths of the root epidermis that are primarily responsible for the absorption of water and minerals from the soil. During the process of transplantation, these fragile root hairs are often broken or lost. Without a sufficient number of root hairs, the seedling cannot absorb enough water to sustain itself in the new environment, which is why many transplanted seedlings fail to grow or survive.

Steel slag can be used for several purposes, and all of the options listed are valid applications.

Statement 1 is correct. Steel slag is a common and cost-effective material for use in road base construction due to its high durability, strength, and drainage properties.

Statement 2 is correct. Crushed steel slag can be used as an amendment for agricultural soil. It can improve drainage, provide some essential nutrients, and even help suppress weeds.

Statement 3 is correct. Steel slag can be partially substituted for some raw materials in cement production, reducing the need for quarrying and lowering the environmental impact of cement manufacturing.

Therefore, the correct answer is 1, 2, and 3.

Statement 1 is Correct: Genetic engineering is fundamental to the development of recombinant vector vaccines. This process involves isolating the gene that codes for a specific antigen (a protein that triggers an immune response) from a pathogen and inserting it into the genetic material of a harmless carrier, known as a vector. Unlike recombinant protein vaccines (like Hepatitis B) where the antigen is produced in a lab, recombinant vector vaccines use the vector to deliver the genetic instructions directly into the human body.

Statement 2 is Correct: Both viruses and bacteria can serve as vectors in these vaccines. Viral vectors, such as Adenoviruses (used in the AstraZeneca/Covishield COVID-19 vaccine) or the Vesicular Stomatitis Virus (used in Ebola vaccines), are common. Bacterial vectors, such as attenuated strains of Salmonella or Mycobacterium bovis (BCG), are also used in research and development to deliver antigens and stimulate a robust immune response.