Inheritance test 7

Gregor Mendel carried out extensive research on pea plants, focusing on seven key characteristics.

These included flower color, flower position, seed shape, seed color, pod shape, pod color, and stem height.

Notably, Mendel did not investigate stem position, making option B the correct answer.

Therefore, the correct answer is B, "Stem position".

Genetics encompasses the study of genes, inheritance, and variation in living organisms.

It involves the scientific exploration of heredity, which is the process of passing traits from parents to offspring, and variation.

Gregor Mendel, known as the father of genetics, contributed significantly to this field.

As such, option B, "Heredity + Variation", best describes the study of Genetics.

Heterogametic sex refers to the sex that produces two types of gametes in relation to sex chromosomes.

In the XO-XX and XY-XX systems, males are the heterogametic sex, producing X and Y (or O) sperm.

Therefore, the correct answer is C, "i and ii only".

The genetic identity of a human male is fundamentally determined by the sex chromosomes.

In humans, males have an XY sex chromosome configuration, which differs from the XX configuration found in females.

Therefore, the correct answer is A, "Sex-chromosome".

The inheritance of the X chromosome in a male occurs through the maternal lineage.

Males have XY chromosomes inherited respectively from mother and father.

Therefore, a man's X chromosome can only come from his mother, who herself inherits her X chromosomes from her parents.

Hence, a man can inherit his X chromosome from his maternal grandmother or maternal grandfather.

Haemophilia is an X-linked recessive disorder affecting the ability of blood to clot.

XhY represents a male individual (Y chromosome) carrying the recessive trait (h) for haemophilia on his X chromosome.

As males have only one X chromosome, a single recessive trait for haemophilia will display the condition.

Therefore, the correct answer is C, "XhY".

The fundamental unit that controls heredity is the gene.

A gene is a section of DNA that holds the instructions to make specific proteins, determining an organism's traits.

Although the genome, chromosomes, and genotype are related to heredity, only the gene directly controls hereditary traits.

Therefore, the correct answer is D, "Gene".

In human beings, the 23rd pair of chromosomes differentiates males from females.

Males have one X and one Y chromosome, with the Y chromosome being shorter.

The SRY gene, located at the tip of the Y-chromosome's short arm, is responsible for determining sex.

Therefore, the correct answer is B, "SRY".

The term 'phenotype' is used in genetics to describe the observable manifestation of a trait.

The phenotype is determined by the organism's genotype, which is its genetic makeup, and environmental influences.

The other options provided do not accurately describe a phenotype.

Therefore, the correct answer is B, "Appearance of a trait".

In the field of genetics, a gene is recognized as the fundamental unit of heredity.

Genes hold the critical information necessary to express a particular trait in an organism.

These genes are meticulously arranged on chromosomes, which serve as the vehicles for transmitting genetic information.

Therefore, the correct answer is C, "Gene".

The law of independent assortment, one of Mendel's key laws, asserts that the inheritance of one genetic character has no effect on the inheritance of another.

This law essentially maintains that the alleles of separate genes are passed independently of one another to offspring.

The law primarily applies to genes located on different, nonhomologous chromosomes.

Therefore, the correct answer is D, "Law of Independent Assortment".

Mendel's law of segregation suggests that the alleles of a gene separate during the formation of gametes.

This principle is best demonstrated in a genetic cross where both parents express the dominant trait but some offspring exhibit the recessive trait, as in the cross Aa × Aa.

This pattern of inheritance could only occur if homologous chromosomes separate during meiosis.

Therefore, the correct answer is D, "Aa × Aa".

Gene linkage refers to the phenomenon where genes that are located on the same chromosome tend to stay together.

The physical linkage or association between genes is, therefore, described as gene linkage.

Other options listed here, such as crossing over, recombination, and synapsis, play roles in genetic interactions but do not define the physical relationship between genes.

Hence, the correct answer is D, "Gene linkage".

Among Mendel's genetic laws, the law of segregation is accepted universally and does not have any known exceptions.

This law states that the two alleles for each trait segregate during the formation of gametes and one allele from each parent combines during fertilization.

While other Mendelian laws, such as the law of dominance and the law of independent assortment, have certain exceptions, the law of segregation holds true in all cases.

The determination of a child's sex is an independent event, and each new child's sex is not influenced by the sex of the previous children.

Therefore, regardless of the number of existing children and their sexes, the probability of having a girl or a boy is always 50% for each new child.

The other options listed (10%, 20%, and 100%) do not represent the correct statistical probability for the gender of the next child.

As such, the correct answer is C, "50%".

In contemporary genetic terminology, Mendel's factor is referred to as a gene. Mendel posited that hereditary traits are determined by discrete units of inheritance.

Each individual unit, or gene, operates independently in an individual's genome. This Mendelian concept suggests that the inheritance of a trait is based on the transmission of these units.

Every individual inherits one gene from each parent, thus resulting in a pair of genes for any given trait.

Therefore, the correct answer is B, "Gene".

In a dihybrid cross, the phenotypic ratio is typically 9:3:3:1.

This ratio translates to 9 offspring with round yellow seeds, 3 with round green seeds, 3 with wrinkled yellow seeds, and 1 with wrinkled green seeds.

Therefore, the number of F2 generation offspring with round yellow seeds is 9.

Thus, the correct answer is B, "9".

Genes are understood to be segments of DNA.

These segments of DNA carry genetic information and are responsible for its inheritance from one generation to the next.

While genes are found on chromosomes and can be transcribed into mRNA, their fundamental structure is composed of DNA.

Therefore, the correct answer is B, "DNA".

The ABO blood grouping in humans exemplifies both multiple allelism and co-dominance.

Multiple allelism is a scenario where more than two alleles exist for a given gene on the same locus of homologous chromosomes. This is evident in the ABO blood group system.

Co-dominance, on the other hand, refers to a situation where alleles that do not display a dominance-recessive relationship express independently when present together. This is seen in how the A and B alleles both express in blood type AB.

Therefore, the answer is E, "Both B and C".

Both Haemophilia A and B are classified as X-linked recessive disorders. This means the alleles causing these conditions are located on the X-chromosome.

Since males have one X and one Y chromosome, they are more likely to express X-linked disorders as they have only one version of each X-chromosome gene.

In contrast, females have two X-chromosomes, and thus two copies of each gene, which can mask the effect of a recessive allele on one X-chromosome.

Therefore, the correct answer is A, "X-Chromosome".

Haemophilia is a condition caused by a mutation in a gene located on the X-chromosome, making it an X-linked disorder.

This disorder is recessive, meaning two copies of the mutated gene must be present for the disorder to manifest. This is less likely in females as they have two X-chromosomes and thus two copies of each gene.

Males, however, have only one X-chromosome. If the X-chromosome they inherit carries the mutation, they will have haemophilia.

Accordingly, the correct answer is C, "This disease is due to an X-linked recessive mutation".

Linkage of genes can be altered through the process of genetic crossing over, which occurs during the prophase of meiosis I.

The other options listed – synapsis, chromosomal pairing, and synaptic formation – are related to the interaction of chromosomes but do not directly result in gene recombination.

Therefore, the correct response to this question is C, "Genetic crossing over."

Mendel’s law of segregation posits that during gamete formation, alleles for each gene segregate so that each gamete carries only one allele for each gene.

This law is also known as the Doctrine of gamete purity, signifying that each gamete remains pure for the trait it carries.

Therefore, the correct option to this question is C, "Doctrine of gamete purity".

The principle of independent assortment is applicable only to factors or genes located on different chromosomes.

If genes are linked and situated on the same chromosome, independent assortment is not possible.

Therefore, the correct response to this question is A, "When genes are linked and located on the same chromosomes."

All the variations of a particular gene, referred to as multiple alleles, reside at the same position or locus on a chromosome.

Although they occupy the same locus, they influence the same trait differently.

Hence the correct answer to this question is B, "At the identical spot on the chromosome."

Holandric genes refer to the genes that exist solely on the Y-chromosome.

These genes contribute to the development of male-specific attributes and features, including initiating the transformation of the embryo into a male.

Consequently, the correct reply to this question is B, "Y-chromosome."

The number of linkage groups in an organism is equal to the quantity of its homologous chromosome pairs.

As Drosophila has four pairs of homologous chromosomes, it has four linkage groups.

Therefore, the correct response to this question is A, "4."

A dominant gene is one that influences the phenotype regardless of whether it's in a homozygous or heterozygous state.

This means it can express its phenotype even in the presence of a recessive allele.

Therefore, the correct response to this question is C, "It shows its effect in both homozygous and heterozygous states."