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Bihar Board Class 12 (Science) Genetics and Evolution — practice questions — page 3

Explore 116 free Genetics and Evolution questions in Bihar Board Class 12 (Science) Biology. Open each question or exercise to read its content, reference answers and available explanation.

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Genetics and Evolution questions and exercises with answers

Showing questions 61–90 of 116.

In honey bees, drones (male bees) develop fromRead the answer and worked solution →Haemophilia and colour blindness are inherited asRead the answer and worked solution →In a monohybrid cross of Tt × Tt, the F2 PHENOTYPIC ratio is:Read the answer and worked solution →Down syndrome is most commonly caused by:Read the answer and worked solution →Mendel's Law of Independent Assortment is best illustrated by the F₂ ratioRead the answer and worked solution →The Hershey-Chase experiment used radioactive isotopes to labelRead the answer and worked solution →DNA polymerase synthesises a new DNA strand in which direction?Read the answer and worked solution →The START codon in eukaryotic mRNA translation is:Read the answer and worked solution →Order the flow of genetic informationRead the answer and worked solution →Charles Darwin's mechanism of evolution is best described as:Read the answer and worked solution →In a DIHYBRID cross of YyRr × YyRr, the F2 phenotypic ratio is:Read the answer and worked solution →Haemophilia and colour blindness are MORE COMMON in MALES than females because they are:Read the answer and worked solution →Mendel conducted his classic genetics experiments using:Read the answer and worked solution →A trait controlled by three or more genes whose effects add up, producing a continuous range of phenotypes, is calledRead the answer and worked solution →Sickle cell anaemia is caused by:Read the answer and worked solution →If two genes on the same chromosome show a recombination frequency of 1%, they are approximatelyRead the answer and worked solution →In humans, the sex of a child is determined at fertilisation byRead the answer and worked solution →In the human ABO blood group system, a person with blood group AB has the genotype:Read the answer and worked solution →In Mendel's monohybrid cross of tall × dwarf pea plants, the phenotypic ratio in the F₂ generation wasRead the answer and worked solution →A tall pea plant is crossed with a dwarf plant. Half the offspring are tall and half are dwarf. The genotype of the tall parent must beRead the answer and worked solution →The Meselson-Stahl experiment proved that DNA replication isRead the answer and worked solution →During transcription, the strand of DNA actually read by RNA polymerase isRead the answer and worked solution →Which eukaryotic RNA polymerase synthesises the mRNA precursor (hnRNA)?Read the answer and worked solution →Which of the following is the universal start codon?Read the answer and worked solution →Approximately how much of the human genome codes for proteins?Read the answer and worked solution →The Central Dogma of molecular biology states that genetic information flows:Read the answer and worked solution →Okazaki fragments are produced during DNA replication on which strand?Read the answer and worked solution →Translation of mRNA into protein occurs on which cellular structure?Read the answer and worked solution →Introns are best described asRead the answer and worked solution →A nucleosome consists ofRead the answer and worked solution →

Worked practice questions

In honey bees, drones (male bees) develop from

  1. unfertilised haploid eggs
  2. fertilised diploid eggs
  3. fertilised eggs with an extra Y chromosome
  4. asexual budding from worker bees
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Correct answer: A. unfertilised haploid eggs

Honey bees use haplo-diploidy. Queens and workers (females) develop from fertilised, diploid eggs. Drones (males) develop from unfertilised eggs and are haploid — they have only one set of chromosomes.

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Haemophilia and colour blindness are inherited as

  1. autosomal dominant traits
  2. autosomal recessive traits
  3. X-linked recessive traits
  4. Y-linked traits
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Correct answer: C. X-linked recessive traits

Both haemophilia and colour blindness are X-linked recessive. Males (one X) show the trait whenever they inherit the bad allele females (two X's) need two copies and are usually only carriers. That's why these conditions appear far more often in boys.

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In a monohybrid cross of Tt × Tt, the F2 PHENOTYPIC ratio is:

  1. $1:2:1$
  2. $9:3:3:1$
  3. $3:1$
  4. $1:1$
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Correct answer: C. $3:1$

Monohybrid F2 phenotypic ratio = 3:1 (3 dominant : 1 recessive). Genotypic ratio is 1:2:1 (TT:Tt:tt). 9:3:3:1 is dihybrid F2; 1:1 is test cross result.

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