Genetic Mcq Test - 1 (State PMT) - NEET MCQ

Agrobacterium tumefaciens and Tumor-Inducing Plasmids
Agrobacterium tumefaciens is a soil bacterium that is known for its ability to cause tumor formation in plants. This is achieved through the transfer of a large plasmid, which contains specific genes that induce the tumor formation. The plasmid responsible for this phenomenon is known as the Ti (tumor-inducing) plasmid.
Explanation of the options:
A: Ti plasmid: This is the correct answer. Agrobacterium tumefaciens contains a large plasmid called the Ti plasmid, which induces tumor formation in plants.
B: Ri plasmid: This is not the correct answer. Ri plasmid is found in Agrobacterium rhizogenes, another species of Agrobacterium that causes hairy root disease in plants.
C: Recombinant plasmid: This is not the correct answer. Recombinant plasmids are artificially created plasmids that are used for genetic engineering purposes.
D: Shine Delgrano sequence: This is not the correct answer. Shine Delgrano sequence refers to a specific sequence found in mRNA molecules that is involved in translation initiation.
In conclusion, the correct answer is A: Ti plasmid. Agrobacterium tumefaciens contains a large plasmid called the Ti plasmid, which induces tumor formation in plants.

To determine the number of types of gametes produced in a trihybrid cross, we need to consider the number of possible combinations of alleles for each gene.
In a trihybrid cross, there are three pairs of genes, let's call them Aa, Bb, and Cc. Each pair can produce two different types of gametes: one carrying the dominant allele (A, B, or C) and one carrying the recessive allele (a, b, or c).
The number of types of gametes produced can be calculated by multiplying the number of possible combinations for each pair of genes:
Number of types of gametes produced = Number of combinations for gene A x Number of combinations for gene B x Number of combinations for gene C
For each pair of genes, there are two possible combinations (dominant allele or recessive allele). Therefore, for three pairs of genes, there will be 2 x 2 x 2 = 8 possible combinations.
So, the correct answer is option D: 8.
Key Points:
- A trihybrid cross involves three pairs of genes.
- Each gene pair can produce two types of gametes (dominant allele or recessive allele).
- The number of types of gametes produced in a trihybrid cross is calculated by multiplying the number of combinations for each gene pair.
- For three pairs of genes, there are 2 x 2 x 2 = 8 possible combinations of gametes.

The functional complex comprising a cluster of genes including structural gene, a promoter gene, an operator gene, and a regulator gene was discovered by Jacob and Monod (1961).

• Background: The discovery of the functional complex was a significant advancement in the understanding of gene regulation and the control of gene expression.


• Researchers: The discovery was made by François Jacob and Jacques Monod, who were French biologists.


• Experiment: Jacob and Monod conducted their experiments using the bacterium Escherichia coli (E. coli).


• Operon Concept: They proposed the concept of the operon, which is a functional unit of DNA comprising a cluster of genes involved in a common metabolic pathway.


• Components of the Operon: The operon consists of several components:




• Structural Gene: The structural gene encodes a specific protein or enzyme involved in a particular metabolic pathway.


• Promoter Gene: The promoter gene is responsible for initiating the transcription of the structural gene.


• Operator Gene: The operator gene acts as a switch, controlling the access of RNA polymerase to the structural gene.


• Regulator Gene: The regulator gene produces a regulatory protein that can bind to the operator gene and control gene expression.




• Regulation of Gene Expression: Jacob and Monod's discovery of the operon provided insights into the mechanisms of gene regulation, such as how certain genes are turned on or off depending on the metabolic needs of the cell.

Overall, Jacob and Monod's discovery of the functional complex comprising a cluster of genes and their proposal of the operon concept revolutionized the field of molecular biology and laid the foundation for future studies on gene regulation.

Trait studied by Mendel in garden pea:

• Axial flower position: This trait is not mentioned as a recessive character, so it is not the correct answer.


• Green cotyledon color: This trait is mentioned as the correct answer for a recessive character studied by Mendel in garden pea.


• Green pod color: This trait is not mentioned as a recessive character, so it is not the correct answer.


• Yellow seed color: This trait is not mentioned as a recessive character, so it is not the correct answer.

Therefore, the correct answer is Green cotyledon color, which was a recessive character studied by Mendel in garden pea.

Explanation:
When an F1 individual is crossed with either of its two parents, it is known as a backcross.
- Test cross: A test cross is a cross between an F1 individual and a homozygous recessive individual to determine the genotype of the F1 individual.
- Back cross: A backcross is a cross between an F1 individual and one of its parents. It is used to introduce or reinforce a particular trait from one of the parents.
- Reciprocal cross: A reciprocal cross is a pair of crosses between a male of one strain or species and a female of another strain or species, and vice versa. It is used to determine if the sex of the parent influences the inheritance pattern.
- Monohybrid cross: A monohybrid cross is a cross between two individuals that differ in only one trait.
In this case, the F1 individual is crossed with one of its parents, which is a backcross. This cross is performed to study the inheritance of traits from the parent to the F1 individual and potentially introduce or reinforce specific traits in the offspring.

Explanation:
Introduction:
Mendel's dihybrid test cross ratio is a ratio proposed by Gregor Mendel to determine the genotype of an individual for two different traits. In this test cross, the individual with the unknown genotype is crossed with a homozygous recessive individual.
Options:
A: 9 : 3 : 3 : 1
B: 1 : 1 : 1 : 1
C: 1 : 2 : 2 : 4 : 1 : 2 : 1 : 2 : 1
D: 3 : 1
Explanation:
The correct answer is option B: 1 : 1 : 1 : 1.
Mendel's dihybrid test cross ratio is derived from the principle of independent assortment. According to this principle, the alleles for different traits segregate independently during gamete formation. Therefore, when a dihybrid individual is crossed with a homozygous recessive individual, the phenotypic ratio of the offspring can be used to determine the genotype of the dihybrid individual.
In the case of a dihybrid test cross, where the individual with the unknown genotype is crossed with a homozygous recessive individual, the expected phenotypic ratio of the offspring is 1 : 1 : 1 : 1. This means that for every four offspring, one will show the dominant phenotype for both traits, one will show the recessive phenotype for both traits, one will show the dominant phenotype for the first trait and the recessive phenotype for the second trait, and one will show the recessive phenotype for the first trait and the dominant phenotype for the second trait.
Therefore, option B: 1 : 1 : 1 : 1 is the correct dihybrid test cross ratio proposed by Mendel.

To determine the incomplete dominance ratio of Red : Pink : White, we need to understand the concept of incomplete dominance.
Incomplete dominance occurs when neither of the alleles is completely dominant over the other, resulting in a blending of traits. In this case, we are considering the color of flowers, where red (RR) is completely dominant over white (rr), and the heterozygous genotype (Rr) results in a pink color.
Given that, let's analyze the options:
A: 1 : 2 : 1
- This ratio suggests that for every 1 red flower, there are 2 pink flowers and 1 white flower.
- This ratio is consistent with incomplete dominance, as the heterozygous genotype (Rr) produces pink flowers.
B: 1 : 1 : 2
- This ratio suggests that for every 1 red flower, there is 1 pink flower and 2 white flowers.
- This ratio does not align with incomplete dominance, as it suggests that the heterozygous genotype (Rr) produces white flowers instead of pink.
C: 1 : 2 : 2
- This ratio suggests that for every 1 red flower, there are 2 pink flowers and 2 white flowers.
- This ratio does not align with incomplete dominance, as it suggests that the heterozygous genotype (Rr) produces more white flowers than pink.
D: 2 : 2 : 1
- This ratio suggests that for every 2 red flowers, there are 2 pink flowers and 1 white flower.
- This ratio does not align with incomplete dominance, as it suggests that the heterozygous genotype (Rr) produces more red flowers than pink.
Therefore, the correct answer is A: 1 : 2 : 1, which represents the incomplete dominance ratio of Red : Pink : White.

Contrasting Characters in Mendel's Study with Garden Pea:
Mendel chose several pairs of contrasting characters in his study with garden pea. These characters were important in his experiments to understand the principles of inheritance. Here are the pairs of contrasting characters chosen by Mendel:
1. Round vs. Wrinkled Seeds: Mendel studied the inheritance of seed shape in peas, with the round seed being the dominant trait and the wrinkled seed being the recessive trait.
2. Yellow vs. Green Seed Color: Another pair of characters studied by Mendel was seed color, with yellow seeds being dominant and green seeds being recessive.
3. Tall vs. Dwarf Plant Height: Mendel investigated the inheritance of plant height. Tall plants were dominant, while dwarf plants were recessive.
4. Flower Color: Mendel also studied the inheritance of flower color in his experiments. He observed the contrast between purple flowers (dominant) and white flowers (recessive).
5. Pod Color: Another pair of characters studied by Mendel was pod color. He observed green pods (dominant) and yellow pods (recessive).
6. Pod Shape: Mendel also investigated the inheritance of pod shape. He observed that inflated pods were dominant, while constricted pods were recessive.
7. Flower Position: The final pair of contrasting characters in Mendel's study was flower position. He observed that axial flowers (located on the main stem) were dominant, while terminal flowers (located at the ends of branches) were recessive.
Therefore, Mendel chose a total of 7 pairs of contrasting characters for his study with garden pea.

Explanation:
The term 'allelomorphic' refers to the concept of alleles, which are different forms of the same gene. Alleles can exist in different versions, resulting in variations in traits or characteristics. The term 'allelomorphic' implies:
- A pair of contrasting characters: Alleles can be either dominant or recessive, and when two different alleles are present in an individual, they can result in a pair of contrasting characters or traits.
- For example, in Mendelian genetics, the gene for flower color in pea plants has two alleles - one for purple flowers (P) and one for white flowers (p). When an individual has two alleles for the same character, they may be either homozygous (having two identical alleles) or heterozygous (having two different alleles).
Therefore, the correct answer is B: A pair of contrasting characters.

When homozygous dominant plant(red flowered) is crossed with homozygous recessive plant(white flowered) ..then the F1 progeny consists of only the dominant trait...i.e. all red flowered plants...acc. to .LAW OF DOMINANCE....

Explanation:
To determine the color of the flower in the F1 progeny, we need to understand the principles of Mendelian genetics and the inheritance patterns of flower color in snapdragons.
- In snapdragons, flower color is determined by a single gene with two alleles: the dominant allele for red flower color (R) and the recessive allele for white flower color (r).
- Homozygous red flowered snapdragons have the genotype RR, and homozygous white flowered snapdragons have the genotype rr.
- When these two parents are crossed, the offspring will inherit one allele from each parent, resulting in the genotype Rr.
- The phenotype, or observable trait, of the flower color is determined by the genotype. In this case, the dominant allele for red flower color (R) will determine the phenotype, resulting in pink flowers.
- Therefore, the color of the flower in the F1 progeny resulting from the cross between a homozygous red and a homozygous white flowered snapdragon will be pink.
Key Points:
- Flower color in snapdragons is determined by a single gene with two alleles: red (R) and white (r).
- Homozygous red snapdragons have the genotype RR, and homozygous white snapdragons have the genotype rr.
- The cross between a homozygous red and a homozygous white snapdragon will result in offspring with the genotype Rr.
- The dominant allele for red flower color (R) will determine the phenotype, resulting in pink flowers in the F1 progeny.

Chromosome Theory of Inheritance:
The Chromosome Theory of Inheritance is a fundamental concept in genetics that explains how traits are passed from parents to offspring. It states that genes are located on specific segments of chromosomes and are responsible for the inheritance of traits.
The postulation of the Chromosome Theory of Inheritance is credited to Sutton and Boveri. Here are the key points about their contribution:
1. Walter Sutton:
- Sutton was an American biologist who proposed the Chromosome Theory of Inheritance in 1902.
- He studied the process of cell division and observed that chromosomes segregate and distribute in a predictable manner during cell division.
- Sutton hypothesized that chromosomes carry hereditary information and suggested that they are the physical basis of inheritance.
2. Theodor Boveri:
- Boveri was a German biologist who independently proposed the Chromosome Theory of Inheritance around the same time as Sutton.
- He conducted experiments with sea urchin eggs and observed that abnormal chromosome distribution led to abnormal development in the offspring.
- Boveri concluded that chromosomes play a crucial role in determining the characteristics of an organism.
3. Collaboration:
- Sutton and Boveri's work overlapped, and they independently arrived at similar conclusions.
- Their research findings complemented each other and provided strong evidence for the Chromosome Theory of Inheritance.
- Their collaborative efforts solidified the acceptance of this theory among the scientific community.
In conclusion, the Chromosome Theory of Inheritance was postulated by Sutton and Boveri. Their work revolutionized the field of genetics and paved the way for further advancements in understanding how traits are inherited.

Explanation:
Drosophila melanogaster is a species of fruit fly commonly used in genetic research. It has a specific number of chromosomes, including autosomes and sex chromosomes.
Autosomes:
- Autosomes are non-sex chromosomes, and they determine the characteristics and traits of an organism.
- Drosophila melanogaster has three pairs of autosomes.
Sex Chromosomes:
- Sex chromosomes determine the sex of an organism.
- In Drosophila melanogaster, there is one pair of sex chromosomes.
Therefore, the correct answer is:
Answer: D
- 3 pairs of autosomes and 1 pair of sex chromosomes.

The tendency of offspring to differ from parents is called variation.
Explanation:
Variation refers to the differences or variations that exist among individuals of the same species. These variations can be observed in various traits such as physical characteristics, behavior, and genetic makeup. Here are the reasons why offspring tend to differ from their parents:
1. Genetic recombination: Offspring inherit a combination of genes from both parents through sexual reproduction. This process leads to the mixing and shuffling of genetic material, resulting in new combinations of traits in the offspring.
2. Mutations: Mutations are random changes in the DNA sequence that can occur during the replication process. These changes can introduce new traits or variations in the offspring that were not present in the parents.
3. Environmental factors: The environment plays a significant role in shaping the traits of an organism. Different environmental conditions can influence the expression of certain genes, leading to variations in the offspring.
4. Adaptation: Offspring may exhibit variations that provide them with a better chance of survival and reproduction in their specific environment. This process, known as adaptation, allows species to evolve and better adapt to changing conditions over time.
Overall, the tendency of offspring to differ from their parents is essential for the survival and evolution of species. It allows for the exploration of new traits and adaptations that can be beneficial in different environments.

To determine the number of genotypes formed in F2 progeny obtained from self-pollination of a dihybrid F1, we need to understand the concept of dihybrid cross and the principles of Mendelian genetics.
Dihybrid Cross:
A dihybrid cross involves the crossing of two individuals that are heterozygous for two different traits. Each trait is controlled by two alleles, and the alleles segregate independently during gamete formation. This means that the alleles for one trait can combine randomly with the alleles for the other trait.
Principles of Mendelian Genetics:
1. Law of Segregation: During gamete formation, the alleles for each gene segregate (separate) independently of the alleles for other genes.
2. Law of Independent Assortment: Genes for different traits segregate independently of one another during gamete formation.
Explanation:
In the given scenario, the F1 generation is dihybrid, meaning that it is heterozygous for two different traits. Let's assume that the traits are AaBb, where A and B represent the dominant alleles and a and b represent the recessive alleles.
When the F1 generation undergoes self-pollination, the possible gametes produced will be:
- Gametes from the Aa genotype: AB, Ab, aB, ab
- Gametes from the Bb genotype: AB, Ab, aB, ab
To determine the genotypes in the F2 progeny, we need to perform a Punnett square analysis using the possible gametes from the F1 generation.
The Punnett square will have four rows and four columns, representing the possible combinations of the gametes. The genotypes obtained in the F2 progeny will be determined by the combination of alleles from the gametes.
The genotypes obtained in the F2 progeny will be:
- AABB
- AABb
- AaBB
- AaBb
- AABb
- AAbb
- AaBb
- Aabb
- aaBB
- aaBb
- AaBb
- Aabb
- AaBB
- AaBb
- aaBb
- aabb
Therefore, there are a total of 16 possible genotypes in the F2 progeny.
Conclusion:
The number of genotypes formed in the F2 progeny obtained from self-pollination of a dihybrid F1 is 16. However, the question asks for the number of types of genotypes, which refers to the distinct combinations of alleles. In this case, there are 9 distinct types of genotypes in the F2 progeny.
Therefore, the correct answer is option A: 9.

Functioning of structural genes is controlled by:
Structural genes play a crucial role in the synthesis of proteins in an organism. The regulation of these genes is necessary to ensure that proteins are produced at the right time and in the right amount. The functioning of structural genes is controlled by various factors, including:
1. Regulator gene:
- The regulator gene is responsible for producing a regulatory protein known as a repressor or activator.
- This protein binds to the operator region of the DNA and regulates the transcription of structural genes.
- It can either activate or inhibit the transcription process, depending on the specific gene and cellular conditions.
2. Operator:
- The operator is a DNA sequence located near the structural genes.
- It acts as a binding site for the regulatory protein produced by the regulator gene.
- The binding of the regulatory protein to the operator can either block or allow the RNA polymerase to bind to the promoter region and initiate transcription.
3. Promoter:
- The promoter is a DNA sequence located upstream of the structural genes.
- It acts as a binding site for RNA polymerase, which is responsible for transcribing the DNA into RNA.
- The promoter region determines the specificity and efficiency of transcription initiation.
4. Ligase:
- Ligase is an enzyme involved in the DNA replication and repair processes.
- It is not directly involved in the regulation of structural genes.
- However, it plays a crucial role in maintaining the integrity of the DNA molecule, which is essential for proper gene expression.
In summary, the functioning of structural genes is controlled by the regulator gene, operator, and promoter. These components work together to regulate the transcription process and ensure the production of proteins in a controlled manner. Ligase, on the other hand, is not directly involved in the regulation of structural genes but is important for maintaining the integrity of the DNA molecule.

An organism with two identical alleles of a gene in a cell is called:
The correct answer is Homozygous.
Explanation:
- Homozygous: Homozygous refers to the condition where an organism has two identical alleles of a particular gene.
- When both alleles are the same, it is referred to as homozygous.
- Homozygous individuals can be either homozygous dominant (having two dominant alleles) or homozygous recessive (having two recessive alleles).
- In a homozygous individual, the alleles can be represented by either uppercase letters (AA) for dominant alleles or lowercase letters (aa) for recessive alleles.
- Homozygosity can be important in genetics, as it determines the expression of certain traits or diseases.
- For example, in Mendelian genetics, a homozygous dominant individual (AA) will always express the dominant trait, while a homozygous recessive individual (aa) will express the recessive trait.
Summary:
An organism with two identical alleles of a gene in a cell is called homozygous. Homozygosity can determine the expression of traits or diseases in an individual.

Explanation:
Mendel's observation that certain characters do not assort independently refers to the phenomenon of linkage of characters. Later research confirmed that this phenomenon is due to the physical association of genes located on the same chromosome. Here is a detailed explanation of the options:
Amitosis:
- Amitosis refers to the direct division of a cell's nucleus without undergoing the usual process of mitosis.
- It does not explain the observed phenomenon of certain characters not assorting independently.
Linkage of characters:
- This is the correct answer.
- Linkage of characters refers to the situation where genes for two different traits are located close together on the same chromosome.
- As a result, these genes tend to be inherited together and do not assort independently during the formation of gametes.
- This phenomenon violates Mendel's principle of independent assortment and was later explained by the discovery of genetic linkage.
Dominance of one trait over the other:
- Dominance refers to the situation where one allele of a gene masks the expression of another allele.
- While dominance can affect the expression of traits, it does not explain the observed phenomenon of certain characters not assorting independently.
Crossing-over:
- Crossing-over refers to the exchange of genetic material between homologous chromosomes during meiosis.
- While crossing-over can lead to the recombination of genes and the creation of new combinations of traits, it does not directly explain the observed phenomenon of certain characters not assorting independently.
In conclusion, the correct answer is B: Linkage of characters.

Answer:
The Nobel prize for the concept of jumping genes was awarded to Barbara McClintock.
Here is a detailed explanation:
Introduction:
- The concept of jumping genes, also known as transposable elements, refers to genetic elements that have the ability to move from one location to another within a genome.
- This phenomenon was first discovered by Barbara McClintock in the 1940s.
Barbara McClintock:
- Barbara McClintock was an American scientist who conducted groundbreaking research in the field of genetics.
- She conducted her research primarily on maize (corn) plants.
- McClintock observed unusual patterns of inheritance in the coloration of maize kernels, which led her to discover the concept of jumping genes.
Discovery of Jumping Genes:
- McClintock noticed that certain genes in maize had the ability to move within the genome, leading to changes in the physical characteristics of the plant.
- She conducted extensive experiments and observed the movement of these genes, which challenged the traditional understanding of genetic inheritance.
Significance of the Discovery:
- McClintock's discovery of jumping genes revolutionized the field of genetics.
- It provided evidence that genes were not fixed entities but could change their position within the genome.
- This discovery had significant implications for understanding the complexity of gene regulation and genetic diversity.
Nobel Prize:
- In recognition of her groundbreaking discovery, Barbara McClintock was awarded the Nobel Prize in Physiology or Medicine in 1983.
- She became the first and only woman to receive an unshared Nobel Prize in that category.
- The Nobel Prize acknowledged her significant contribution to the understanding of genetic inheritance and the concept of jumping genes.
In conclusion, Barbara McClintock was awarded the Nobel Prize for her discovery of jumping genes, which challenged the traditional understanding of genetics and revolutionized the field.

Restrictions endonuclease because it's help in cut DNA fragment.

Explanation:
The 1:2:1 ratio observed in the F2 generation indicates the phenomenon of incomplete dominance. Here's a detailed explanation:
Incomplete dominance:
Incomplete dominance is a genetic phenomenon where neither of the two alleles is completely dominant over the other, resulting in an intermediate phenotype in heterozygotes.
Key points:
- In the given scenario, the 1:2:1 ratio suggests that there are three possible genotypes and three corresponding phenotypes in the F2 generation.
- Let's assume that the pink flower color is controlled by a single gene with two alleles: A (red) and a (white).
- In incomplete dominance, when a homozygous red flower (AA genotype) is crossed with a homozygous white flower (aa genotype), the F1 generation will have all pink flowers.
- The pink color in the F1 generation is an intermediate phenotype between red and white, which indicates incomplete dominance.
- When two pink flowers (Aa genotype) from the F1 generation are crossed in the F2 generation, the resulting ratio of red:pink:white is 1:2:1.
- This ratio indicates that the pink phenotype is not a result of blending or codominance, but rather a result of incomplete dominance.
Conclusion:
Therefore, based on the 1:2:1 ratio observed in the F2 generation, we can conclude that the phenomenon involved is incomplete dominance.

Transgenic Crops and Genetic Engineering:

Transgenic crops are plants that have been genetically engineered to possess certain desirable traits, such as natural resistance to insect pests. This is achieved by introducing genes from other organisms into the plant's genome, allowing it to produce proteins that can protect against pests.
Identifying the Transgenic Plant:

The question asks for a transgenic plant among the given options. Let's analyze each option to determine which one fits the criteria:
A: Tobacco and cotton - Both tobacco and cotton plants can be genetically modified to develop resistance to insect pests through genetic engineering techniques. Therefore, option A is a transgenic plant.
B: Tomato and rice - While both tomato and rice plants can be genetically modified, it is not specified if they have been modified for insect resistance. Without further information, we cannot determine if this option represents a transgenic plant.
C: Maize and sugarcane - Similar to the previous option, maize and sugarcane can be genetically modified, but it is not specified if they have been modified for insect resistance. Without more details, we cannot confirm if this option represents a transgenic plant.
D: Tomato and wheat - Again, both tomato and wheat plants can be genetically modified, but it is not stated if they have been modified for insect resistance. Without additional information, we cannot conclude if this option represents a transgenic plant.
Conclusion:

Based on the information provided, option A (Tobacco and cotton) can be identified as a transgenic plant as both tobacco and cotton plants can be genetically engineered to develop natural resistance to insect pests.

Explanation:

The given cross involves the inheritance of flower color in Mirabilis plants. The plant with pink flowers is crossed with a white-flowered plant. The flower color in Mirabilis is determined by a pair of alleles, with red (RR) being dominant over white (rr) and producing pink flowers (Rr).

The expected phenotypic ratio can be determined using Punnett square analysis:

Step 1:

Write down the genotypes of the parents:

• Pink-flowered plant: Rr


• White-flowered plant: rr

Step 2:

Create a Punnett square by combining the alleles from each parent:

	R	r
R	RR	Rr
r	rR	rr

Step 3:

Determine the possible phenotypes of the offspring:

• RR: Red-flowered


• Rr: Pink-flowered


• rr: White-flowered

Step 4:

Count the number of each phenotype:

• Red-flowered (RR): 0


• Pink-flowered (Rr): 2


• White-flowered (rr): 2

The phenotypic ratio is therefore 2:2, which simplifies to 1:1. Therefore, the correct answer is option B: pink : white (1 : 1).

As there is no any effect of gibberellins on genot... moreype so this cross is simply TT(tall) x tt( dwarf) Hence 100% progeny is tall.

Explanation:
When different alleles are present in the same genotype, it is called heterozygous. Here's a detailed explanation:
- Homozygous: Homozygous refers to a genotype where both alleles for a specific gene are the same. For example, if an organism has two identical alleles for the gene controlling eye color (e.g., BB or bb), it is homozygous for that trait.
- Heterozygous: Heterozygous refers to a genotype where two different alleles are present for a specific gene. For example, if an organism has one dominant allele and one recessive allele for the gene controlling eye color (e.g., Bb), it is heterozygous for that trait.
- Diallelic: Diallelic refers to a situation where there are two different alleles of a gene present in a population. It does not specifically refer to the presence of different alleles in the same genotype.
- Polyallelic: Polyallelic refers to a situation where there are more than two different alleles of a gene present in a population. Again, it does not specifically refer to the presence of different alleles in the same genotype.
Therefore, the correct answer is heterozygous (B).

Sex-linked Inheritance
Sex-linked inheritance refers to the inheritance of traits that are controlled by genes located on the sex chromosomes (X and Y chromosomes). In humans, the X chromosome is larger and carries more genes compared to the Y chromosome. Since males have one X and one Y chromosome, while females have two X chromosomes, certain genetic disorders or traits can be more commonly observed in one sex than the other.

Associated Traits:

• Night-blindness: Night-blindness is associated with a condition known as retinitis pigmentosa, which is caused by mutations in the genes located on the X chromosome. This disorder is more commonly observed in males as they have only one X chromosome.


• Muscular dystrophy: Muscular dystrophy is a genetic disorder characterized by the progressive weakening and loss of muscle tissue. The most common form of muscular dystrophy, called Duchenne muscular dystrophy, is caused by mutations in the dystrophin gene located on the X chromosome. This disorder primarily affects males.


• Astigmatism: Astigmatism is a refractive error of the eye that causes blurred vision. It is not specifically associated with sex-linked inheritance and can affect both males and females equally.


• Polydactyly: Polydactyly is a condition in which an individual has extra fingers or toes. It is not typically associated with sex-linked inheritance and can occur in both males and females.

Therefore, the correct answer is B: muscular dystrophy.

Haemophilia is:
Definition:
- Haemophilia is a medical condition characterized by a deficiency or absence of a clotting factor in the blood, leading to excessive bleeding and poor blood clotting.
Cause:
- Haemophilia is usually an inherited disorder caused by a mutation in one of the genes responsible for clotting factors VIII (haemophilia A) or IX (haemophilia B).
- In rare cases, haemophilia can also occur due to spontaneous mutations.
Mode of Inheritance:
- Haemophilia is an X-linked recessive disorder, which means that the faulty gene responsible for the condition is located on the X chromosome.
- As a result, haemophilia is more common in males because they have one X chromosome, while females have two X chromosomes.
Signs and Symptoms:
- Excessive bleeding from minor cuts or injuries
- Frequent nosebleeds
- Easy bruising
- Prolonged bleeding after surgery or dental procedures
- Joint pain and swelling (hemophilic arthropathy) due to recurrent bleeding into the joints
- Blood in urine or stool
Diagnosis:
- Haemophilia can be diagnosed through blood tests that measure the levels of clotting factors VIII and IX.
- Genetic testing can also be done to identify the specific mutation causing haemophilia.
Treatment:
- There is no cure for haemophilia, but it can be managed through various treatment options, including:
- Replacement therapy: Infusing the missing clotting factor into the bloodstream to restore normal clotting.
- Desmopressin (DDAVP): A medication that stimulates the release of stored clotting factor VIII from blood vessels.
- Gene therapy: Experimental treatment that aims to replace the faulty gene responsible for haemophilia with a functional one.
Conclusion:
- Haemophilia is a deficiency disorder characterized by the absence or deficiency of clotting factors in the blood.
- It is an X-linked recessive disorder, more commonly affecting males.
- Diagnosis is done through blood tests and genetic testing.
- Treatment options include replacement therapy, medications, and gene therapy.

Sex Determination Ratio in an Organism
The sex determination ratio in an organism is given by X/A = 1.5. Let's understand what this means and how it determines the sex of the organism.
Explanation:
- The sex determination ratio compares the number of X chromosomes (representing female sex) to the number of autosomal chromosomes (A).
- In this case, the ratio is 1.5, which means that there are 1.5 times more X chromosomes than autosomal chromosomes in the organism.
Possible Scenarios:
Based on the given sex determination ratio, we can determine the sex of the organism:
- If the ratio is 1 (X/A = 1), it means that there is an equal number of X chromosomes and autosomal chromosomes. This is typical for males in many organisms.
- If the ratio is greater than 1 (X/A > 1), it means that there are more X chromosomes than autosomal chromosomes. This is typical for females in many organisms.
- If the ratio is less than 1 (X/A < 1), it means that there are fewer X chromosomes than autosomal chromosomes. This scenario is not common in most organisms.
Conclusion:
In this case, the sex determination ratio is 1.5 (X/A = 1.5), which means that there are 1.5 times more X chromosomes than autosomal chromosomes in the organism. This scenario is not typical for males or females. However, it is referred to as "super female" or "metafemale" because it indicates an increased number of X chromosomes compared to autosomal chromosomes. Therefore, the correct option is C: super female.

Epistasis implies:
- One pair of genes can completely mask the expression of another pair of genes: This statement is correct. Epistasis refers to the interaction between different genes, where one gene can suppress or mask the expression of another gene. In this case, the presence of one gene can override the effect of another gene, resulting in the absence of its expression.
- One pair of genes independently controls a particular phenotype: This statement is not true for epistasis. Epistasis involves the interaction between genes, and the expression of a phenotype is influenced by the combined effect of multiple genes, rather than a single gene controlling it independently.
- One pair of genes enhances the phenotypic expression of another pair of genes: This statement is not accurate for epistasis. Epistasis can involve the suppression or masking of gene expression, but it does not necessarily enhance the phenotypic expression of another gene pair.
- Many genes collectively control a particular phenotype: This statement is true for epistasis. Epistasis often involves the interaction of multiple genes to collectively control a particular phenotype. The expression of a trait or phenotype can be influenced by the combined effects of several genes interacting with each other.
Therefore, the correct option is A: One pair of genes can completely mask the expression of another pair of genes.

Phenotyped it's means external feature so that it depend upon external changes or features.