All Free Biology MCQs with Answers

• A. R.B.Cs
• B. Body fluids
• C. Saliva
• D. All A, B, C

Explanation: Option D is correct. Yes, blood group antigens can be found in red blood cells (RBCs), body fluids, and saliva.RBCs contain the A, B, and…

• A. BB X Bi
• B. BB X BB
• C. Bi X Bi
• D. Both A and C

Explanation: Option C is correct. The genotype of Sara's parents can also be Bi X Bi.

• A. Man
• B. Monkey
• C. Rat
• D. Chimpanzee

Explanation: The Rh blood group is one of the most complex blood groups known in humans.

• A. Protanopia
• B. Deuteranopia
• C. Tritanopia
• D. Dichromacy

Explanation: Protanopia is a type of color blindness that is caused by a mutation in the gene that codes for the L-cone photoreceptors.

• A. Blue blindness
• B. Green blindness
• C. Red blindness
• D. Color blindness

Explanation: Deuteranopia is a type of color blindness that is caused by a mutation in the gene that codes for the M-cone photoreceptors.

• A. Dominance
• B. Pleiotropy
• C. Epistasis
• D. Gene linkage

Explanation: In Bombay phenotype the phenotypic effect of AB gene located on chromosome number 9 is being interfered by H gene located on chromosome…

• A. 22 homologous pairs of chromosomes
• B. 22 homologous pairs of autosomes
• C. 23 homologous pairs of chromosomes
• D. One pair of sex chromosomes

Explanation: Sex chromosomes are also homologous in female (XX) whereas autosomes are homologous in both male and females both.

• A. It confirms that DNA is the carrier of genetic information
• B. It helps to understand whether the trait in question is dominant or recessive
• C. It confirms that the trait is linked to one of the autosomes
• D. It helps to trace the inheritance of a specific trait

Explanation: Pedigree analysis is a tool used to study the inheritance of traits through generations of a family.

• A. 100%
• B. 0 %
• C. 25%
• D. 50%

Explanation: Color blindness is an X-linked recessive trait. The father, who is normal-visioned, has an X chromosome with the normal vision allele (XN)…

• A. Homozygous sex chromosomes (ZZ) determine female sex in birds
• B. XO type of sex chromosomes determine male sex in grasshoppers
• C. XO condition in humans as found in Turner's syndrome, determines female sex
• D. Homozygous sex chromosomes (XX) produce male in Drosophila

Explanation: The correct answer is that the XO type of sex chromosomes determines male sex in grasshoppers.

• A. Between two genotypes with recessive trait
• B. Between two F1 hybrids
• C. The F1 hybrid with a double recessive genotype
• D. Between two genotypes with dominant trait

Explanation: A test cross is a genetic cross performed to determine the genotype of an organism exhibiting a dominant phenotype.

• A. Tightly linked genes on the same chromosome show higher recombinations
• B. Genes far apart on the same chromosome show very few recombinations
• C. Genes loosely linked on the same chromosome show moderate recombinations
• D. Tightly linked genes on the same chromosome show very few recombinations

Explanation: Linkage refers to the tendency of genes located close to each other on the same chromosome to be inherited together during meiosis.

• A. The discrete unit controlling a particular character is called a factor
• B. Out of one pair of factors, one is dominant, and the other is recessive
• C. Alleles do not show any blending and both the characters recover as such in the F2 generation
• D. Factors occur in pairs

Explanation: Option C is the correct choice because it describes a phenomenon explained by Mendel's law of independent assortment, not the law of…

• A. All color blind
• B. All normal visioned
• C. One-half color blind and one-half normal
• D. Three-fourths color blind and one-fourth normal

Explanation: Color blindness is a recessive, sex-linked trait carried on the X chromosome.

• A. It expresses its effect only in homozygous state
• B. It expresses its effect only in heterozygous condition
• C. It expresses its effect both in homozygous and heterozygous condition
• D. It never expresses its effect in any condition

Explanation: A gene is considered dominant if it expresses its effect in both homozygous (two copies of the dominant allele) and heterozygous (one…

• A. Down's syndrome - 21st chromosome
• B. Sickle cell anaemia - X chromosome
• C. Haemophilia - Y chromosome
• D. Parkinson's disease - X and Y chromosome

Explanation: The correct answer is Option A: Down's syndrome is caused by the presence of an extra copy of chromosome 21, known as trisomy 21.

• A. 9 : 3 : 4
• B. 12 : 3 : 1
• C. 9 : 3 : 3 : 1
• D. 9 : 7

Explanation: The correct answer is 9 : 7 (Option D). Complementary gene interaction occurs when two different genes work in tandem, with the presence…

• A. Genes are located on homologous chromosomes
• B. Genes are linked and located on the same chromosome
• C. Genes are located on non-homologous chromosomes
• D. All of these

Explanation: Independent assortment of genes occurs when genes are located on different chromosomes or far apart on the same chromosome, allowing them…

• A. In humans, the Y chromosome is crucial for male sex determination
• B. The Y chromosome is integral to sex determination in both humans and Drosophila
• C. In Drosophila, the Y chromosome determines femaleness
• D. The Y chromosome contains genes for Klinefelter's syndrome in humans

Explanation: The question explores the different roles of the Y chromosome in sex determination across species.

• A. Colour blind sons and 50% carrier daughters
• B. 50% colour blind sons and 50% carrier daughters
• C. Normal males and carrier daughters
• D. Colour blind sons and carrier daughters

Explanation: In X-linked recessive inheritance, males have one X chromosome and one Y chromosome.