Genetics

Question 1

What is the concept of Pangenesis proposed by Hippocrates?

Answer 1

Pangenesis suggests that “seeds” from all parts of the body are collected in the reproductive organs and transmitted to offspring.

Question 2

What hypothesis did Mendel’s experiments refute?

Answer 2

Mendel’s experiments refuted the Blending Hypothesis, which proposed that traits from parents blend together in offspring.

Question 3

Who is considered the father of genetics and what organism did he use for his experiments?

Answer 3

Gregor Johann Mendel is considered the father of genetics, and he used garden peas for his experiments.

Question 4

What does Mendel’s Law of Segregation state?

Answer 4

The Law of Segregation states that each individual has two alleles for each gene, which segregate during gamete formation, so each gamete receives one allele.

Question 5

How is Mendel’s Law of Independent Assortment demonstrated?

Answer 5

It is demonstrated through dihybrid crosses, showing that genes for different traits can segregate independently during the formation of gametes.

Question 6

Define phenotype and genotype.

Answer 6

henotype: Observable characteristics of an individual.
Genotype: Genetic makeup of an individual.

Question 7

What are true breeders?

Answer 7

True breeders are varieties that produce the same trait over several generations.

Question 8

What is a monohybrid cross and its typical F2 generation ratio?

Answer 8

A monohybrid cross involves crossing two true-breeding plants differing in a single trait, with the F2 generation showing a 3:1 ratio (dominant: recessive).

Question 9

Describe the typical F2 generation ratio observed in dihybrid crosses.

Answer 9

The F2 generation shows a 9:3:3:1 ratio.

Question 10

What is the difference between dominant and recessive alleles?

Answer 10

Dominant alleles mask the expression of recessive alleles in heterozygous individuals.

Question 11

Define homozygous and heterozygous.

Answer 11

Homozygous: Two identical alleles for a trait.
Heterozygous: Two different alleles for a trait.

Question 12

What tool is used to predict the genotypes and phenotypes of offspring from a genetic cross?

Answer 12

A Punnett Square.

Question 13

Provide the genotypic and phenotypic ratios from a cross of Tt (heterozygous tall) plants.

Answer 13

Genotypic Ratio: 1 TT : 2 Tt : 1 tt
Phenotypic Ratio: 3 Tall : 1 dwarf

Question 14

Explain the significance of the 3:1 and 9:3:3:1 ratios.

Answer 14

The 3:1 ratio is observed in the F2 generation of monohybrid crosses, and the 9:3:3:1 ratio is observed in the F2 generation of dihybrid crosses, reflecting Mendel’s laws of segregation and independent assortment.

Question 15

What are the steps to perform a chi-squared test?

Answer 15

1. Calculate the expected values.
2. Use the formula: χ² = Σ (O - E)² / E where O is observed data and E is expected data.
3. Determine degrees of freedom (df = number of categories - 1).
4. Compare the calculated χ² value with a chi-squared table to find the p-value.

Question 16

How do you analyze a human pedigree chart?

Answer 16

Pedigree analysis studies the inheritance patterns of genetic traits in humans. Components include symbols for males (squares), females (circles), and affected individuals (shaded symbols), with generations indicated by Roman numerals.

Question 17

What is the inheritance pattern for recessive traits in a pedigree?

Answer 17

In recessive inheritance, two unaffected heterozygous individuals will have, on average, 25% affected offspring.

Question 18

What is the inheritance pattern for dominant traits in a pedigree?

Answer 18

In dominant inheritance, an affected individual usually has an affected parent.

Question 19

What causes sickle cell anemia, and what is its inheritance pattern?

Answer 19

Sickle cell anemia is caused by a mutation in the beta-globin gene resulting in abnormal hemoglobin (Hb-S), leading to red blood cells sickling. It is inherited in a recessive pattern.

Question 20

What causes cystic fibrosis, and what is its inheritance pattern?

Answer 20

Cystic fibrosis is caused by mutations in the CFTR gene affecting ion transport, leading to thick mucus in various organs. It is inherited in a recessive pattern.

Answer 21

Multiple-choice questions may involve genotypes, phenotypes, Mendel’s laws, Punnett squares, chi-squared test, and pedigree analysis. Essay questions might include detailed explanations of Mendel’s experiments, chi-squared test application, and pedigree analysis for specific disorders