Question 1

What is a common effect associated with Down syndrome?

Accepted Answer

Answer reason: Down syndrome commonly involves congenital cardiac anomalies, especially atrioventricular septal defects; the other options are not characteristic associations.

Question 2

What is the study of genes called?

Accepted Answer

Answer reason: Genetics is the branch of biology that studies genes and heredity; the other options refer to pathology (disease), histology (tissues), and cytology (cells).

Question 3

Which DNA triplet codes for valine?

Accepted Answer

Answer reason: Valine mRNA codons are GUU, GUC, GUA, and GUG. The complementary DNA template triplets are CAA, CAG, CAT, and CAC; among the options only CAT matches.

Question 4

Which congenital disorder is characterized by underdeveloped or absent clavicles, delayed closure of fontanelles, and dental abnormalities?

Accepted Answer

Answer reason: Caused by mutations in the RUNX2 gene, this disorder produces hypoplastic or absent clavicles, delayed cranial suture closure, and distinctive dental anomalies.

Question 5

The first human hormone produced by recombinant DNA technology is?

Accepted Answer

Answer reason: Human insulin was the first therapeutic protein produced using recombinant DNA technology and the first rDNA drug approved (Humulin, 1982). The human insulin gene was inserted into microorganisms (e.g., E. coli/yeast) to biosynthesize the hormone. Progesterone, estrogen, and thyroxin are small molecules typically produced by chemical synthesis and were not the first rDNA products.

Question 6

Theory of Natural selection was proposed by?

Accepted Answer

Answer reason: Charles Darwin formulated the theory of natural selection, proposing that heritable variations that confer survival and reproductive advantages become more common in populations over time. He synthesized this framework in On the Origin of Species (1859). Charles Lyell and James Hutton were geologists known for uniformitarianism, and Carolus Linnaeus developed the system of taxonomy, not the mechanism of evolution.

Question 7

Genetic material of the human body is?

Accepted Answer

Answer reason: DNA is the hereditary material that stores and transmits genetic information in humans, encoded as sequences of nucleotides. It is replicated during cell division to pass traits to daughter cells. Proteins and enzymes are functional gene products rather than the genetic blueprint itself. Sugars are structural components of nucleic acids but are not the genetic material.

Question 8

DNA is found in..?

Accepted Answer

Answer reason: In eukaryotic cells, the vast majority of DNA is packaged as chromosomes within the nucleus. Ribosomes and the Golgi body contain RNA and proteins but no DNA. The cytoplasm itself does not contain DNA, though organelles like mitochondria (not listed) have their own DNA. Therefore, the correct option is the nucleus.

Question 9

The two normal types of sex chromosomes are?

Accepted Answer

Answer reason: In humans, normal sex chromosome complements are XX for females and XY for males. Variants such as XXY and XYY represent aneuploidies due to nondisjunction, associated with Klinefelter and XYY syndromes respectively. Therefore, the only pair listing normal complements is XX and XY.

Question 10

How many mitosis are required to produce 60 seeds?

Accepted Answer

Answer reason: Seed formation involves numerous mitotic divisions during development of the embryo and endosperm, and the number of mitoses varies widely by species and developmental conditions. There is no fixed count of mitotic divisions per seed. In contrast, the number of meiotic events per seed is more defined, but the question asks specifically about mitosis. Therefore, the required number is indefinite.

Question 11

Female chromosome is?

Accepted Answer

Answer reason: In humans, biological sex is determined by the sex chromosomes. Females are typically homogametic with two X chromosomes (46,XX), while males are heterogametic with one X and one Y (46,XY). The Y chromosome carries the SRY gene that initiates testis development; absence of Y leads to ovarian development. Therefore, the female chromosome complement is XX.

Question 12

The number of chromosome in human cell is ____?

Accepted Answer

Answer reason: Human somatic cells are diploid, containing 23 pairs of chromosomes for a total of 46. This includes 22 pairs of autosomes and one pair of sex chromosomes. Gametes are haploid with 23, but typical body cells have 46.

Question 13

What is the shape of DNA called?

Accepted Answer

Answer reason: DNA consists of two antiparallel polynucleotide strands coiled around each other, forming a double helix. The strands are held together by complementary base pairing via hydrogen bonds and stabilized by base stacking interactions. This helical structure explains replication fidelity and genetic information storage.

Question 14

A gene is a functional unit of ___?

Accepted Answer

Answer reason: Genes are segments of DNA that reside on chromosomes and encode functional products such as proteins or functional RNAs. In classical genetics, a gene is considered the functional unit of heredity located on a chromosome. While DNA is the chemical substance, chromosomes are the structures that carry genes. Therefore, the best answer is chromosomes.

Question 15

DNA structure was first described by?

Accepted Answer

Answer reason: James Watson and Francis Crick proposed the double-helix model of DNA in 1953, synthesizing X-ray diffraction data (notably from Rosalind Franklin) and Chargaff’s base-pairing rules. Their model correctly explained complementary base pairing and antiparallel strands. Pasteur and Koch were pioneers in microbiology, and Linnaeus developed taxonomic classification, none of whom described DNA’s structure.

Question 16

Female Chromosome Is?

Accepted Answer

Answer reason: In humans, genetic sex is determined by the combination of sex chromosomes. Females have two X chromosomes (46,XX), while males have one X and one Y chromosome (46,XY). Options YY and YX do not represent a normal female karyotype; XY/YX corresponds to male. Therefore, the female chromosome pair is XX.

Question 17

........ is basic unit of heredity?

Accepted Answer

Answer reason: The gene is the fundamental unit of heredity, carrying the information that determines traits and is passed from parents to offspring. Genes are segments of DNA that encode functional products, typically proteins. Cells are structural and functional units of life, not specifically heredity, and a letter is unrelated biologically.

Question 18

The probability of a baby being a boy or girl depends on the sex chromosome of?

Accepted Answer

Answer reason: Human sex determination depends on whether the fertilizing sperm carries an X or a Y chromosome. The mother’s ovum always contributes an X chromosome, while the father’s sperm contributes either X (producing XX, female) or Y (producing XY, male). Thus, the paternal gamete determines the baby’s sex, making the probability dependent on the father’s sex chromosome.

Question 19

Autosomes in humans are?

Accepted Answer

Answer reason: Humans have 46 chromosomes organized into 23 pairs. Of these, 22 pairs are autosomes that are the same in both sexes, and 1 pair are sex chromosomes (XX or XY). Therefore, the number of autosomal pairs is 22.

Question 20

Mendal is the father of the...?

Accepted Answer

Answer reason: Gregor Mendel’s experiments with pea plants established the basic laws of inheritance, including segregation and independent assortment. These principles laid the foundation for modern genetics. Thus, he is regarded as the father of genetics, not of biology, chemistry, or zoology.

Question 21

______ is the molecule of Heredity?

Accepted Answer

Answer reason: DNA is the primary hereditary molecule in almost all cellular organisms, storing genetic information and replicating accurately during cell division. It encodes genes that direct protein synthesis via transcription and translation. Although some viruses use RNA as their genetic material, DNA is the universal molecule of heredity in cellular life.

Question 22

Chromosome structure can be observed best during ___?

Accepted Answer

Answer reason: Chromosomes are maximally condensed and aligned at the metaphase plate, making individual chromatids and centromeres most distinct for visualization and karyotyping. In prophase, condensation has begun but structure is not yet as clear. By anaphase, sister chromatids separate and stretch toward poles, reducing clarity of intact chromosome morphology. Therefore, metaphase provides the best stage to observe chromosome structure.

Question 23

Which is a genetic disorder?

Accepted Answer

Answer reason: Sickle cell anemia is an inherited autosomal recessive disorder caused by a mutation in the HBB gene leading to hemoglobin S formation. Diabetes and hypertension are multifactorial conditions influenced by genetics and environment but are not single-gene disorders. Typhoid is an infectious disease caused by Salmonella typhi. Therefore, sickle cell anemia is the genetic disorder among the options.

Question 24

Down syndrome is due to..?

Accepted Answer

Answer reason: Down syndrome results from an extra copy of chromosome 21 (trisomy 21), most often due to meiotic nondisjunction, with risk increasing with advanced maternal age. It presents with characteristic facial features, intellectual disability, and common congenital heart defects such as atrioventricular septal defects. Trisomy 18 causes Edwards syndrome, monosomy X causes Turner syndrome, and trisomy 13 causes Patau syndrome, none of which are Down syndrome.

Question 25

Which of the following best describes the genetic inheritance of human AB blood group?

Accepted Answer

Answer reason: AB blood type occurs when both IA and IB alleles are present, and both antigens are expressed equally on red blood cells. This is the definition of codominance. It is not incomplete dominance (no blended phenotype), not a simple Mendelian dominant–recessive pattern, and not a dihybrid cross because it involves a single gene with multiple alleles.

Question 26

Male Sex chromosome is?

Accepted Answer

Answer reason: In humans, the typical male karyotype contains one X and one Y chromosome (XY). The Y chromosome carries the SRY gene that triggers testicular development and male sex differentiation. XX is the typical female karyotype, while XXX and XYY are aneuploidies and not the standard chromosomal pattern for males.

Question 27

Who is considered the father of genetics?

Accepted Answer

Answer reason: Gregor Johann Mendel is considered the father of genetics because his pea plant experiments established the fundamental laws of inheritance (segregation and independent assortment). He demonstrated that traits are passed as discrete units (now called genes) rather than blending. Darwin is associated with evolution by natural selection, Lamarck with inheritance of acquired characteristics, and Watson and Crick with the DNA double-helix structure—not the original inheritance laws.

Question 28

Which one of these is found in human Females only?

Accepted Answer

Answer reason: In typical human sex determination, females have two X chromosomes (46,XX), while males have one X and one Y chromosome (46,XY). An X chromosome is present in both sexes, so it is not female-only. XYY is a male sex chromosome aneuploidy, and the Y chromosome is generally associated with male genetic sex. Therefore, the best answer is XX chromosome.

Question 29

How many chromosomes are there in a human?

Accepted Answer

Answer reason: Humans have 46 chromosomes in most somatic cells, arranged as 23 pairs. Of these, 22 pairs are autosomes and 1 pair are sex chromosomes (XX or XY). Gametes (sperm/ova) are haploid and contain 23 chromosomes, which combine at fertilization to restore the diploid number of 46.

Question 30

Female Chromosome is?

Accepted Answer

Answer reason: In typical human sex determination, females have two X chromosomes (XX), while males usually have one X and one Y chromosome (XY). The presence of a Y chromosome (specifically the SRY gene) generally initiates male sexual development. Therefore, among the choices provided, XX is the correct female chromosomal pattern.

Question 31

In which of the following life processes is the creation of a DNA copy, a basic event?

Accepted Answer

Answer reason: Creating a copy of DNA (DNA replication) is essential before cell division so genetic information can be passed to daughter cells. This is a fundamental requirement for reproduction at the cellular level (mitosis for asexual reproduction/growth and meiosis for sexual reproduction via gamete formation). Respiration, excretion, and circulation do not inherently require genome duplication as their primary defining events. Therefore, reproduction is the best answer.

Question 32

What is the term for a change in the DNA sequence of an organism?

Accepted Answer

Answer reason: A change in the nucleotide sequence of DNA is defined as a mutation. Gene flow refers to movement of alleles between populations, genetic drift is random change in allele frequencies, and natural selection is differential survival/reproduction based on traits. Only mutation directly describes alteration of the DNA sequence itself.

Question 33

What is the basic unit of heredity?

Accepted Answer

Answer reason: The gene is considered the basic unit of heredity because it is the functional segment of DNA that carries information for a trait and can be transmitted from parents to offspring. Chromosomes are larger structures that contain many genes. DNA is the chemical molecule that genes are made of, but “gene” is the unit that is inherited. A cell contains genetic material but is not the basic hereditary unit.

Question 34

Which method is most helpful in identifying chromosomal abnormalities?

Accepted Answer

Answer reason: Karyotyping directly examines the number and structure of chromosomes and can definitively identify aneuploidies (e.g., trisomies) and large structural rearrangements. Ultrasound and serum markers such as hCG and AFP are screening tools that estimate risk or detect associated anomalies but do not visualize chromosomes. Therefore, karyotyping is the most helpful method for identifying chromosomal abnormalities.

Question 35

Humans have _______ of autosomes?

Accepted Answer

Answer reason: Humans have 46 chromosomes total arranged in 23 pairs. Of these, 22 pairs are autosomes (chromosome pairs 1–22) and 1 pair are sex chromosomes (XX or XY). Therefore, the number of autosome pairs in humans is 22.

Question 36

Most common Cell with increase telomerase activity?

Accepted Answer

Answer reason: Telomerase maintains telomere length and is characteristically active in cells that must undergo many rounds of division without progressive telomere shortening. Germ cells have high telomerase activity to preserve genomic stability across generations. Most somatic cells have low/absent telomerase, leading to telomere shortening with age. Many cancers also reactivate telomerase, but among the listed normal cell types, germ cells are the best answer.

Question 37

Which chromosome combination results in a baby girl?

Accepted Answer

Answer reason: In typical human sex determination, an embryo with two X chromosomes (XX) develops female sexual characteristics. The presence of a Y chromosome (as in XY) generally leads to male development due to the SRY gene triggering testes formation. A YY combination is not viable in humans because at least one X chromosome is required for survival.

Question 38

Where is the cell is DNA stored...?

Accepted Answer

Answer reason: In eukaryotic cells, the primary location of genetic material (DNA) is the nucleus, where chromosomes are housed and DNA replication and transcription occur. Ribosomes are the site of protein synthesis and do not store DNA. Although mitochondria contain small amounts of their own DNA, the standard single best answer for where a cell stores DNA is the nucleus.

Question 39

Webbing of the neck is the characteristic feature of?

Accepted Answer

Answer reason: Webbed neck (pterygium colli) is a classic phenotypic feature of Turner syndrome (45,X), often associated with congenital lymphatic dysplasia leading to neck skin folds. Turner syndrome commonly also presents with short stature and gonadal dysgenesis. The other listed conditions have different hallmark findings (e.g., Edwards has clenched fists/rocker-bottom feet; neurofibromatosis has café-au-lait spots/neurofibromas; Fanconi anemia primarily causes bone marrow failure and skeletal anomalies).

Question 40

Haemophilia is more commonly seen in human males than in females because ?

Accepted Answer

Answer reason: Hemophilia A and B are classically inherited as X-linked recessive disorders. Males have only one X chromosome, so inheriting a single affected X results in disease expression. Females typically require two affected X chromosomes to be affected, so most heterozygous females are carriers with little or no symptoms. This inheritance pattern makes the condition much more common in males than females.

Question 41

Number of chromosomes present in sperm..?

Accepted Answer

Answer reason: Human sperm cells are haploid gametes produced by meiosis, so they contain one set of chromosomes (n). In humans, the haploid number is 23 (22 autosomes plus one sex chromosome, X or Y). The diploid number 46 applies to somatic cells and the resulting zygote after fertilization. Therefore, the correct option is 23.

Question 42

Genes that are present on the same chromosomes are said to be?

Accepted Answer

Answer reason: Genes located on the same chromosome are termed "linked genes" because they tend to be inherited together during meiosis. Their physical proximity reduces the likelihood that crossing over will separate them, so they do not assort independently as often as genes on different chromosomes. The other options are not standard genetics terms describing chromosomal co-localization (and "dominant" refers to expression in heterozygotes, not location).

Question 43

Which chromosome combination found in men?

Accepted Answer

Answer reason: Typical human males have one X chromosome and one Y chromosome (46,XY). The presence of the Y chromosome, specifically the SRY gene, initiates testes development and male sexual differentiation. XX is the typical female karyotype, and YY is not a viable normal human sex-chromosome complement.

Question 44

The most common chromosomal disorder causing ambiguous genitalia is?

Accepted Answer

Answer reason: Among the listed chromosomal disorders, Klinefelter syndrome (47,XXY) is the one most associated with atypical/under-virilized male genital development due to primary testicular failure and relative androgen deficiency. Turner syndrome (45,X) typically presents as phenotypic female with streak ovaries rather than ambiguous genitalia. Down syndrome (trisomy 21) and Patau syndrome (trisomy 13) cause multiple congenital anomalies but are not common causes of ambiguous genitalia. Therefore, Klinefelter syndrome is the best answer from the given options.

Question 45

Trisomy (Extra chromosomes)-?

Accepted Answer

Answer reason: Trisomy refers to the presence of an extra chromosome, most classically trisomy 21. Down syndrome is caused by an extra copy of chromosome 21, leading to characteristic phenotypic findings and intellectual disability. The other options are not chromosomal aneuploidy syndromes: hematoma is a localized blood collection, and “mental retardation” is a nonspecific outcome rather than a diagnosis. Therefore, Down's syndrome is the best answer.

Question 46

Who determines the sex of the child in humans?

Accepted Answer

Answer reason: In humans, the mother’s ovum always contributes an X chromosome, while the father’s sperm can contribute either an X or a Y chromosome. Fertilization by an X-bearing sperm results in XX (genetic female), and fertilization by a Y-bearing sperm results in XY (genetic male). Therefore, the father determines the genetic sex of the child based on whether the sperm carries X or Y.

Question 47

How many chromosome in human sperm cell?

Accepted Answer

Answer reason: Human sperm cells are haploid gametes produced by meiosis, so they carry one set of chromosomes (n). In humans, the haploid number is 23, which includes 22 autosomes plus one sex chromosome (X or Y). Upon fertilization, the sperm’s 23 combines with the ovum’s 23 to restore the diploid number of 46 in the zygote.

Question 48

Genetic material of cell is?

Accepted Answer

Answer reason: In most cells, DNA is the hereditary material that stores genetic information in genes and chromosomes. It provides the template for RNA and protein synthesis, enabling cell structure and function to be maintained and passed to daughter cells. Proteins, lipids, and carbohydrates are essential cellular components but do not serve as the primary long-term genetic storage material in cells.

Question 49

Which of the following is a tumor suppressor gene?

Accepted Answer

Answer reason: P53 (TP53) is a classic tumor suppressor gene that helps prevent malignant transformation by sensing DNA damage and triggering cell-cycle arrest (via p21), DNA repair, senescence, or apoptosis. Loss-of-function mutations in p53 remove this checkpoint control, allowing accumulation of mutations and uncontrolled proliferation. In contrast, Ras, Myc, and Src are typically proto-oncogenes that drive growth signaling when activated or overexpressed.

Question 50

DNA fingerprint method is very useful for ?

Accepted Answer

Answer reason: DNA fingerprinting analyzes polymorphic DNA regions (e.g., STRs/VNTRs) that vary among individuals, producing a unique profile. This makes it useful for identity testing and establishing biological relationships (paternity/kinship). The same principle underlies forensic applications by matching biological samples from a crime scene to an individual. Therefore, all listed uses are correct.

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