Genetics Plant Breeding

The evidence of particulate nature for the units of inheritance was first presented by Gregor Mendel. Mendel is recognized as the father of genetics due to his foundational work in elucidating the principles of heredity.

Through his experiments with pea plants, Mendel discovered how traits are passed from one generation to the next through discrete units, which we now refer to as genes. His work laid the groundwork for the understanding of genetic inheritance and demonstrated the concept of dominant and recessive alleles.

Therefore, the correct answer is: Mendel

In plant breeding, the process typically involves several structured steps to ensure the development of new plant varieties with improved traits. The correct sequence of steps is as follows:

1. Creation of variation: This step involves generating genetic variations, often through methods such as hybridization, mutation, or genetic engineering. By introducing varied genetic material, breeders can explore a wide range of potential traits.
2. Selection of superior variants: After variation is created, the next crucial step is to select the most promising variants. This involves evaluating the plants for traits like disease resistance, yield, and climate adaptability, and choosing those that best meet breeding goals.
3. Evaluation of variants: The selected variants undergo rigorous testing and evaluation under different environmental conditions to assess their performance. This step ensures that only those variants that consistently demonstrate superior traits are advanced.
4. Multiplication and distribution: Finally, the successful variants are multiplied on a large scale to produce sufficient seeds or planting material. These are then distributed to farmers and growers for commercial crop production.

Given the options, the correct sequence is:
(B) Creation of variation
(A) Selection of superior variants
(D) Evaluation of variants
(C) Multiplication and distribution

Therefore, the correct answer is: (B), (A), (D), (C)

In the field of agriculture, the term "heterosis" refers to the phenomenon where the offspring of two different strains exhibit greater strength, growth, fertility, and survivability than either parent. This biological improvement of hybrids is essential for enhancing crop yields and livestock productivity. The term was coined to describe the beneficial effects observed in hybrid organisms.

Among the options given, the term "heterosis" was coined by George Harrison Shull in the year 1914. Shull's pioneering work laid the foundation for modern hybrid breeding practices, significantly impacting agricultural science and production systems worldwide.

This breakthrough concept has led to the development and application of hybrid vigor in various crops and animals, highlighting the importance of genetic diversity and hybridization strategies in agriculture.

Therefore, the correct answer is: Shull, 1914

To determine which statements about genes are correct, let's analyze each statement one by one:

• (A) Genes are located on chromosomes: This statement is correct. Genes are segments of DNA and are indeed located on chromosomes, which serve as their structural components in the cell nucleus.
• (B) Split genes are composed of exons only: This statement is incorrect. Split genes, or interrupted genes, consist of both exons and introns. Exons are the coding sequences, while introns are non-coding sequences that are removed during RNA splicing.
• (C) Genes move from one linkage group to another: This statement is incorrect under normal circumstances. Genes are linked together in groups based on their proximity on a chromosome, and they do not typically move between these linkage groups except in rare cases of translocation or some types of genetic recombination.
• (D) Chromosomes with identical arms on which genes are located are known as isochromosomes: This statement is correct. Isochromosomes have identical arms due to a misdivision at the centromere, resulting in one arm being duplicated.

Based on the analysis, statements (A) and (D) are correct, but statement (B) is incorrect due to its description of split genes. Therefore, none of the options exactly fit the complete accuracy, and there may be a misinterpretation in identified choices. However, if guided by the structure given, option identifying (A), (B), and (D) suggests correct place for factual errors retaining check on question choices. Caution points toward wary context consideration.

Tissue culture is a technique of growing cells, tissues, or organs in a controlled artificial environment. The father of tissue culture is recognized as Haberlandt. He was a pioneer in the field and made significant contributions that laid the groundwork for modern tissue culture methods. His theoretical work and ideas set the foundation for later practical applications of tissue culture in biology and agriculture.