Genetics And Plant Breeding — Part 2 MCQs with Explanations

Zinc is essential for biosynthesis of 3-IAA in plants. Zinc activates tryptophan synthetase, which regulates the synthesis of tryptophan, involved in the biosynthesis of indoleacetic acid (IAA). Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. It is the best-known of the auxins and has been the subject of extensive studies by plant physiologists. IAA is a derivative of indole, containing a carboxymethyl substituent.

Photophosphorylation takes place during the day. Photophosphorylation is the conversion of ADP to ATP using the energy of sunlight by activation of PSII. This involves the splitting of the water molecule into oxygen and hydrogen protons (H + ), a process known as photolysis. As this process happens in the presence of sunlight, and thus takes place during the day.

The situations that lead to cross-pollination are Protandry, Heterostyly and herkogamy . Protandry is the condition of flowers whose male parts mature before the female ones. Heterostyly is a morphological and reproductive polymorphism in which plant populations are composed of two (distyly) or three (tristyly) floral morphs that differ reciprocally in the height of their stigmas and anthers. Herkogamy is the spatial separation of the anthers and stigma in hermaphroditic angiosperms. It is a common strategy for reducing self-fertilization. All the above condition increases the chances of cross-pollination in plants.

The genetic material of Prion is protein . Prions are believed to be the causative agents of a group of rapidly progressive neurodegenerative diseases called transmissible spongiform encephalopathies, or prion diseases. They are infectious isoforms of a host-encoded cellular protein known as the prion protein. A prion is composed of an abnormally folded protein that causes progressive neurodegenerative conditions, with two of the most notable being Bovine spongiform encephalopathy.

The correct answer is Option A: 48 . Let's break down why: Chromosomes are structures that contain the genetic information (DNA) of an organism. Each species has a specific number of chromosomes . Potato ( *Solanum tuberosum* ) is a tetraploid plant. Tetraploid means it has four sets of chromosomes. The basic chromosome number (x) in *Solanum* species is 12. Therefore, the chromosome number in potato (2n = 4x) is 4 * 12 = 48 .

A. In plants with large genomes, the chromosomes are significantly larger than the animal chromosomes. It is true. B. It is also true, the species having lower chromosome numbers have longer chromosomes. C. It is false, that generally, dicots have a lower number of chromosomes than monocots. The number of chromosomes does not depend on monocot or dicot type. D. It is also true that dicots have shorter chromosomes than monocots.

The principle of limiting factors was proposed by Blackman in 1905. The principle of limiting factors says that the maximum obtainable rate of photosynthesis is limited by whichever basic resource of plant growth is in the least supply. The availability of energy and moisture varies geographically. Although the process of photosynthesis is affected by more than one factor, its rate will be determined by the factor which is in the least supply.

There are 16 main elements that are required for the healthy growth and development of plants. These are carbon (C), oxygen (O), hydrogen (H), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo) and chlorine (Cl).

ER is Endoplasmic Reticulum and is generally present in all differentiated eukaryotic cells. The endoplasmic reticulum (ER) is a highly convoluted, netlike meshwork that extends throughout the cytoplasm. ER plays a crucial role in the synthesis, modification, transport, and degradation of membrane and secretory proteins, and is the site for biosynthesis, processing, and transport of several lipids, and regulation of cytosolic calcium levels.

The cell of embryosac which releases one chemical to guide the movement of pollen towards the ovule is Synergids. Synergid cells are two specialized cells that lie adjacent to the egg cell in the female gametophyte of angiosperms and play an essential role in pollen tube guidance and function. Defensin-like polypeptide LUREs are pollen tube attractants secreted from synergid cells.

Ganga-4 is a Double cross hybrid . It is a cross-product of CM 400 × CM 300 × CM 602. Matures in 100 - 105 days. Plants have medium-thick stems with long narrow green leaves. This cultivar also possesses moderate resistance to downey mildew, leaf blight, rust stem borer and lodging. Suitable for all maize growing areas.

W. C. Rontgen discovered X-rays first. W. C. Rontgen reported the discovery of X-rays in December 1895 after seven weeks of assiduous work during which he had studied the properties of this new type of radiation able to go through screens of notable thickness. He named them X-rays to underline the fact that their nature was unknown. X-radiation is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3 × 10 16 Hz to 3 × 10 19 Hz) and energies in the range 145 eV to 124 keV.

When the composite sample is reduced to required size it is to be submitted to seed testing lab is Submitted sample . The composite sample is formed by combining and mixing all the primary samples taken from the lot or container or bag. Submitted sample is a sample submitted to the testing station.

A Group of plants with similar characteristics of any rank is termed a taxon . A taxon is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. A taxonomic unit, whether named or not: i.e. a population, or group of populations of organisms that are usually inferred to be phylogenetically related and which have characters in common that differentiate.

The F 1 ratio of a backcross in a monohybrid cross is 1 : 1 . The mating of a hybrid organism (offspring of genetically unlike parents) with one of its parents or with an organism genetically similar to the parent is known as a Back cross. The backcross is useful in genetics studies for isolating (separating) certain characteristics in a related group of animals or plants.

The total of deleterious genes present in species is known as Genetic load. A genetic alteration that increases an individual's susceptibility or predisposition to a certain disease or disorder is known as a deleterious gene. Deleterious mutation load is the main contributing factor to genetic load overall. Load depends only on the deleterious mutation rate and not on the selection coefficient.

Bread wheat is Auto-allopolyploid. Autoallopolyploid, is having one set of chromosomes (or one genome) in a more than diploid state. Bread Wheat (Decaploid triticale) (AABBDDRRRR) is an example of auto-allopolyploidy. This plant has two copies of each of the three genomes of bread wheat (ABD) and four copies of that of rye genome (R). Thus the rye genome is in autotetraploid condition.

The longest phase in the cell cycle prophase, from the given options. The first and longest phase of mitosis is prophase. During prophase, chromatin condenses into chromosomes, and the nuclear envelope (the membrane surrounding the nucleus) breaks down. In animal cells, the centrioles near the nucleus begin to separate and move to opposite poles of the cell.

D-genome of common cultivated wheat has been contributed by Ae squarosa . The D genome of allohexaploid bread wheat (Triticum aestivum, 2n = AABBDD) is the least diverse of the three wheat genomes and is unarguably less diverse than that of diploid progenitor Aegilops tauschii (2n = DD). Aegilops tauschii (synonyms Aegilops squarrosa, Triticum tauschii), is a wild goatgrass that was one of the parent species of bread wheat.

The remenants of nucellus forms Perisperm . Perisperm is the nutritive tissue of a seed derived from the nucellus and deposited externally to the embryo sac. It is the nutritive tissue of a seed that includes both endosperm and perisperm formed after the process of fertilization.

The 'operon concept' of gene regulation was proposed by Jacob and Monod. Operon Theory is the concept of gene regulation proposed by François Jacob and Jacques Monod (1961). An operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. The repressor encoded by a regulatory gene binds to the operator and represses the transcription of the operon.

The outer membrane of mitochondria has Porin . The outer mitochondrial membrane fully surrounds the inner membrane, with a small intermembrane space in between. The outer membrane has many protein-based pores that are big enough to allow the passage of ions and molecules as large as a small protein known as porins.

The Law of segregation is the law that explains the ratio obtained by crossing Rr × Rr. The law of segregation states that each individual that is a diploid has a pair of alleles for a particular trait. Each parent passes an allele at random to their offspring resulting in a diploid organism. The allele that contains the dominant trait determines the phenotype of the offspring.

The process in which seeds are formed but an embryo develops without fertilization is Apomixis. Apomixis (asexual seed formation) is the result of a plant gaining the ability to bypass the most fundamental aspects of sexual reproduction: meiosis and fertilization. Without the need for male fertilization, the resulting seed germinates a plant that develops as a maternal clone.

The end product of photosynthesis is Starch. Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Starch is the primary product of photosynthesis. Starch represents the main plant storage carbohydrate that provides energy during heterotrophic growth.

The resulting two daughter cells produced by the bridge-breakage fusion cycle will have Both Duplication and Deficiency. Breakage-fusion-bridge (BFB) cycle is a mechanism of chromosomal instability, discovered by Barbara McClintock in the late 1930s. The BFB cycle begins when the end region of a chromosome, called its telomere, breaks off. When that chromosome subsequently replicates it forms two sister chromatids which both lack a telomere.

Passive absorption of minerals takes place through the Ionic exchange. Ion exchange is a reversible process, and the ion exchanger can be regenerated or loaded with desirable ions by washing with an excess of these ions. In plants and animals, mineral absorption, also called mineral uptake is how minerals enter the cellular material, typically following the same pathway as water.

An individual with a gametic chromosome number is a Haploid. Haploid refers to the presence of a single set of chromosomes in an organism's cells. A haploid describes a cell that contains a single set of chromosomes. The term haploid can also refer to the number of chromosomes in egg or sperm cells, which are also called gametes. In humans, gametes are haploid cells that contain 23 chromosomes, each of which a one of a chromosome pair that exists in diploid cells.

Chiasmata terminalization refers to the movement of chiasmata (the points where crossing over has occurred between homologous chromosomes) towards the ends of the chromosomes. This process is a key feature of the Diplotene stage of Prophase I in meiosis. During Diplotene, the homologous chromosomes begin to separate but remain attached at chiasmata, which gradually move toward the telomeres — a process known as terminalization. Pachytene is the stage where crossing over occurs, Zygotene is when synapsis starts, and Leptotene is the initial stage where chromosomes begin to condense. Therefore, chiasmata terminalization specifically occurs during Diplotene.

Pure line selection is mainly done for Self-pollinated crops . Pure-line selection involves selecting and breeding progeny from superior organisms for several generations until a pure line of organisms with only the desired characteristics has been established. Basically, a pure line refers to a progeny of a single, homozygous, and self-pollinated plant.

Cytoplasmic sterility is governed by Plasma genes. Cytoplasmic male sterility is under extranuclear genetic control. It shows non-Mendelian inheritance, with male sterility inherited maternally. In general, there are two types of cytoplasm: N (normal) and aberrant S (sterile) cytoplasms. And plasma genes are a self-replicating extranuclear determiner of hereditary characteristics.

If the plant is infected with one disease, it makes the plant resistant to other diseases. This phenomenon is known as Cross protection . Cross-protection, also known as “pre-immunization" is a method of plant virus control, whereby a plant is deliberately infected with a mild strain of a virus to protect the plant against damage caused by a more severe strain of the same virus.

The concept of physiological races was given by Barrus (1911). Physiological races are strains of a single pathogen species differing in their ability to attack different varieties of the same host species. The physiological race is a biotype or group of biotypes within a taxonomic group distinguished by some physiological peculiarity as host preference, chemical dependence, or pathogenicity used especially of economically important fungi, insects, or bacteria.

Dr. Har Govind Khurana was awarded the Nobel Prize in 1968 for his work on Genetic code and in vitro synthesis of DNA. Har Gobind Khorana was an Indian American biochemist. While on the faculty of the University of Wisconsin-Madison, he shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that showed the order of nucleotides in nucleic acids, which carry the genetic code of the cell and control the cell's synthesis of proteins.

Protein synthesis takes place in Ribosome. A ribosome is an intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell. The ribosome reads the messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to synthesize proteins.

Selfing reduces heterozygosity. Selfing (self-pollination) is the ultimate form of inbreeding or mating among close relatives. It can create yield loss when inbreeding depression, defined as a lower survival and reproduction of inbred relative to outbred progeny, is present. Selfing increases homozygosity and reduces heterozygosity at a rate of 0.50 per generation. Increased homozygosity can uncover recessive deleterious variants and lead to inbreeding depression unless it is countered by the loss of these variants by genetic purging.

The wide crossing is also known as distant hybridization. Wide crossing refers to the process of undertaking a cross where one parent is from outside the immediate gene pool of the other. Wide hybridization or distant hybridization is crossing between two different species or genera and has been used successfully to move genes and to create new crop species.

The seed multiplication ratio of rapeseed red gram, hybrid maize, sorghum and jute is 1 : 100. The seed Replacement Ratio is a measure of how much of the total cropped area was sown with certified seeds in comparison to farm-saved seeds. The process of seed planning involves the use of the Seed Multiplication Ratio (SMR) in the computation and estimation of seed demand in the country.

Helper T-cells are the component of the immune response that is crippled in AIDS. HIV can destroy CD4 cells by direct virus cytotoxicity and indirectly through the host response against HIV-infected cells or gp120-targeted cells. Cells of the macrophage lineage are generally not destroyed but serve as a reservoir of the virus. HIV also causes functional impairment in T cells, B cells and monocytes.

Pusa Ratna is a new variety of Mungbean . It is Suitable for the Kharif season. The average seed yield is 12.0 q/ha Pods are synchronous in maturity and mature in 65 - 70 days. This variety is tolerant to the mungbean yellow mosaic virus.