Module 2

Question 1

Developed the principles of inheritance by experimenting on pea plants; Austrian monk

Answer 1

Gregor Mendel

Question 2

Traits are determined by discrete units called factors (later known as genes). These factors come in pairs, one inherited from each parent.

Answer 2

Particulate Inheritance (Mendel’s Conclusions)

Question 3

In a pair of genes, one form (dominant) can mask the expression of the other form (recessive). The recessive trait only appears in the offspring if inherited from both parents.

Answer 3

Dominance and Recessivity (Mendel’s Conclusions)

Question 4

During gamete formation (sperm and egg cells), the alleles (different versions of a gene) in a gene pair segregate, with only one allele going into each gamete. This ensures that offspring inherit one allele from each parent.

Answer 4

Law of Segregation (Mendel’s Laws)

Question 5

Gene pairs for different traits assort independently during gamete formation. The inheritance of one trait does not influence the inheritance of another. (This applies to genes located on different chromosomes)

Answer 5

Law of Independent Assortment (Mendel’s Laws)

Question 6

When an organism inherits unlike alleles (heterozygous), the phenotype (observable trait) is usually determined by the dominant allele. The recessive allele remains hidden but can be expressed in the offspring if inherited from both parents. However, Mendel also acknowledged exceptions to complete dominance, noting incomplete dominance (where both alleles are partially expressed) and codominance (where both alleles are fully expressed).

Answer 6

Law of Dominance (Incomplete Dominance and Codominance are refinements) (Mendel’s Laws)

Question 7

Mendel’s Laws

Answer 7

1. Law of Segregation
2. Law of Independent Assortment
3. Law of Dominance (Incomplete Dominance and Codominance are refinements)

Question 8

Somatic cells (body cells) in an organism are _______ , meaning they contain two complete sets of chromosomes, one from each parent.

Answer 8

Diploid

Question 9

are haploid, containing only one set of chromosomes. This reduction in chromosome number, achieved through meiosis (cell division), allows for the creation of genetically diverse offspring during fertilization.

Answer 9

Gametes

Question 10

Types of Zygosity

Answer 10

1. Homozygous Dominant (HH)
2. Heterozygous (Hh)
3. Homozygous Recessive (hh)

Question 11

An organism inherits two dominant alleles

Answer 11

Homozygous Dominant (HH)

Question 12

An organism inherits one dominant and one recessive allele

Answer 12

Heterozygous (Hh)

Question 13

An organism inherits two recessive alleles

Answer 13

Homozygous Recessive (hh)

Question 14

basic units of heredity, located on chromosomes and composed of DNA.

Answer 14

Gened

Question 15

is the observable expression of the genotype, influenced by both genes and environmental factors.

Answer 15

Phenotype

Question 16

refers to its complete genetic makeup, including all the alleles it carries.

Answer 16

Genotype

Question 17

are a visual tool used to predict the probability of offspring genotypes and phenotypes based on parental genotypes.

Answer 17

Punnett Squares

Question 18

Modes of Inheritance: Beyond Simple Mendelian Genetics

Answer 18

1. Incomplete Dominance
2. Codominance
3. Polygenic Inheritance
4. Sex-linked Inheritance
5. Pleiotropy

Question 19

Neither allele is completely dominant, resulting in a blending of the traits in the heterozygous individual

Answer 19

Incomplete Dominance

Question 20

Both alleles are fully expressed in the heterozygous individual

Answer 20

Codominance

Question 21

Multiple genes contribute to a single trait, with each gene having a small effect. Environmental factors can also influence the final outcome

Answer 21

Polygenic Inheritance

Question 22

Genes located on the sex chromosomes (X and Y) can exhibit unique inheritance patterns. Traits controlled by genes on the X chromosome can be passed from mother to son without being expressed in the mother herself.

Answer 22

Sex-linked Inheritance

Question 23

A single gene can influence multiple traits (e.g., sickle-cell disease affects both red blood cell shape and susceptibility to infection)

Answer 23

Pleiotropy

Question 24

Role of Environment

Answer 24

1. Gene Expression
2. Phenotypic Plasticity
3. Environmental Triggers

Question 25

Environmental factors like diet, light, temperature, and toxins can influence how genes are expressed. They can modify the activity of genes without changing the underlying DNA sequence.

Answer 25

Gene Expression

Question 26

Organisms with the same genotype can exhibit different phenotypes based on their environment. For example, some plants may grow taller in response to increased sunlight.

Answer 26

Phenotypic Plasticity

Question 27

Certain genes may require specific environmental cues to be activated. For instance, some flowering plants only bloom under specific day-length conditions.

Answer 27

Environmental Triggers

Question 28

Inheriting two copies (one from each parent) results in death, usually at the embryonic stage. These alleles are rare as they are typically purged from the population quickly.

Answer 28

Dominant Lethals

Question 29

An organism dies only if it inherits two copies of the allele (one from each parent). These alleles can persist in a population for many generations if carriers (heterozygotes) do not exhibit any negative effects.

Answer 29

Recessive Lethals

Question 30

results in death, usually at the embryonic stage. These alleles are rare as they are typically purged from the population quickly.

Answer 30

Dominant Lethals

Question 31

A dominant allele at one gene can completely suppress the expression of another gene.

Answer 31

Dominant Epistasis

Question 32

The effect of a gene is only expressed when a specific recessive allele is present at another gene.

Answer 32

Recessive Epistasis

Question 33

refers to a single gene having multiple, seemingly unrelated effects on an organism. This phenomenon occurs because a gene product (protein) can play a role in various biological processes. For example, a gene mutation affecting pigment production might influence eye color, skin color, and hair color.

Answer 33

Pleiotropy

Question 34

In female mammals, one of the X chromosomes is randomly inactivated in each cell early in embryonic development.

Answer 34

X-Inactivation

Question 35

ensures that females generally have the same dosage of X-linked genes as males (who have only one X chromosome).

Answer 35

X-Inactivation

Question 36

The inactivated X chromosome is condensed into a structure called

Answer 36

Barr body

Question 37

X-inactivation can lead to interesting phenomena like:

Answer 37

Carrier females & Calico cats

Question 38

Females who are heterozygous for an X-linked trait (one normal allele and one mutant allele) may exhibit a mix of cells expressing the normal or mutant version of the gene, resulting in a mosaic phenotype.

Answer 38

Carrier Females

Question 39

The random inactivation of X-linked genes controlling coat color in cats can lead to the development of a _____ pattern, with patches of orange, black, and white fur.

Answer 39

Calico Cats

Question 40

arises when an organism has genetically distinct cell populations due to a mutation occurring at some point during development. This can result in a patchwork of different phenotypes within the same individual.

Answer 40

Mosaicism

Question 41

This genetic disorder can cause skin and nerve tumors, and its severity can vary depending on the extent of mosaicism.

Answer 41

Neurofibromatosis

Question 42

This condition results in patches of lighter skin and hair due to a mosaic pattern of melanocyte (pigment cell) development.

Answer 42

Piebaldism

Question 43

tool used to trace the inheritance of a trait through generations in a family.

Answer 43

Pedigree Analysis

Question 44

refers to a group of individuals with genetically identical DNA. These individuals arise from a single parent cell through asexual reproduction.

Answer 44

Clones

Question 45

Bacteria reproduce asexually by binary fission, where a single cell divides into two genetically identical daughter cells.

Answer 45

Bacterial Fission

Question 46

techniques like budding or grafting can produce clones. These methods involve taking a piece of tissue from a parent plant and using it to generate a new, genetically identical individual.

Answer 46

Vegetative Propagation

Question 47

cloning can also be achieved artificially through techniques like

Answer 47

Somatic Cell Nuclear Transfer (SCNT) & Embryo Splitting

Question 48

This technique involves separating the blastocyst stage embryo (a cluster of cells) of a fertilized egg into multiple individual embryos. These embryos can then be implanted into surrogate mothers to develop into genetically identical offspring.

Answer 48

Embryo Splitting:

Question 49

technique used to create a clone from an adult cell.

Answer 49

Somatic cell nuclear transfer (SCNT)

Question 50

Somatic Cell Nuclear Transfer (SCNT) process

Answer 50

1. ***Nucleus Removal*:** A nucleus is extracted from a somatic cell (body cell) of the donor organism. 2. ***Egg Cell Preparation*:** An egg cell from a female of the same species is obtained and its own nucleus is removed (enucleation). 3. ***Nuclear Transfer*:** The nucleus from the donor somatic cell is carefully inserted into the enucleated egg cell. 4. ***Cellular Reprogramming*:** The egg cytoplasm reprograms the somatic cell nucleus, essentially reversing its specialized state and returning it to an embryonic state. 5. ***Embryonic Development*:** The reconstructed cell (now containing the donor nucleus) undergoes cell division and begins to develop into an embryo. 6. ***Implantation and Birth*:** The cloned embryo can be implanted into a surrogate mother for gestation and birth.

Question 51

SCNT was famously used to create

Answer 51

Dolly the sheep

Question 52

technique used to introduce foreign genetic material (DNA or RNA) into cells.

Answer 52

Vector delivery

Question 53

Engineered viruses can efficiently deliver genes into host cells, but safety concerns exist due to the potential for insertional mutagenesis (unintended insertion of the gene).

Answer 53

Viral vectors

Question 54

These are circular DNA molecules commonly used in bacteria, and they can be modified to carry foreign genes for delivery into cells.

Answer 54

Plasmids

Question 55

These vectors are based on synthetic materials or modified molecules and offer improved safety profiles compared to viral vectors, but their transfection efficiency can be lower.

Answer 55

Non-viral vectors

Question 56

refers to the process by which the heritable characteristics of a population change over successive generations. This intricate dance of life shapes the diversity of species we see on Earth today.

Answer 56

Evolution

Question 57

There are several key mechanisms driving evolution:

Answer 57

- ***Natural Selection*:** This is the prevailing theory of evolution, explained in detail below. - ***Genetic Drift*:** Random fluctuations in allele frequencies within a population can lead to evolution, especially in small populations. - ***Gene Flow*:** The movement of genes between populations through migration can introduce new genetic variations. - ***Mutations*:** Changes in the DNA sequence can create new alleles and fuel the process of evolution.

Question 58

This is the prevailing theory of evolution

Answer 58

Natural Selection

Question 59

Random fluctuations in allele frequencies within a population can lead to evolution, especially in small populations.

Answer 59

Genetic Drift

Question 60

The movement of genes between populations through migration can introduce new genetic variations.

Answer 60

Gene Flow

Question 61

Changes in the DNA sequence can create new alleles and fuel the process of evolution.

Answer 61

Mutations

Question 62

system for organizing Earth's history into major divisions based on significant geological and biological events. It provides a chronological framework for understanding the fossil record and the evolution of life on our planet.

Answer 62

Geological Time Scale

Question 63

This is the earliest eon, characterized by the formation of the Earth's crust and the emergence of the first primitive life forms.

Answer 63

Eoarchean Eon

Question 64

This eon saw the rise of the first complex single-celled organisms, the development of photosynthesis, and the formation of the first supercontinents.

Answer 64

Proterozoic Eon

Question 65

proposed the theory of inheritance of acquired characteristics, suggesting that traits acquired during an organism's lifetime could be passed on to offspring. This theory, however, has been refuted by modern genetics.

Answer 65

Jean-Baptiste Lamarck

Question 66

credited with developing the theory of evolution by natural selection.

Answer 66

Charles Darwin, along with Alfred Russel Wallace

Question 67

theory of evolution by natural selection. This theory proposes that:

Answer 67

- Individuals within a population exhibit variations in traits. - Some of these variations are heritable. - Individuals with traits better suited to the environment are more likely to survive and reproduce, passing on those advantageous traits to their offspring. - Over generations, this process leads to the gradual adaptation of a population to its environment.

Question 68

This is the cornerstone of Darwinian evolution. It explains how heritable traits that enhance survival and reproduction become more common in a population over time.

Answer 68

Natural Selection

Question 69

independently developed a theory of evolution by natural selection around the same time as Darwin. Their ideas were presented jointly in 1858.

Answer 69

Alfred Russel Wallace

Question 70

though not directly involved in evolutionary theory, laid the foundation of modern genetics with his experiments on pea plants.

Answer 70

Gregor Mendel

Question 71

reveal gradual transitions between species, supporting the idea of descent with modification.

Answer 71

Fossils

Question 72

allows scientists to determine the age of fossils, placing them within a chronological framework and confirming the order of their appearance on Earth.

Answer 72

Radiometric dating

Question 73

Evidences for Evolution

Answer 73

1. Paleontological Evidence (Fossils & Dating Techniques) 2. Biogeographical Evidence (Distribution of Species) 3. Comparative Anatomy (Homologous & Analogous Structures) 4. Embryology (Early Developmental Similarities) 5. Contrivances (Complex Adaptations) 6. Vestigial Structures (Remnants of the Past) 7. Biochemistry and Physiology (Shared Molecular Similarities) 8. Selection (Direct Observation) 9. Adaptations (Traits for Survival and Reproduction)

Question 74

permanent changes in the DNA sequence of an organism. They can arise due to errors during DNA replication, exposure to mutagens (environmental factors like radiation), or mobile genetic elements.

Answer 74

Mutation

Question 75

refers to the movement of genes between populations. This can occur through migration of individuals or exchange of gametes (pollen, sperm, eggs) between populations.

Answer 75

Gene flow

Question 76

During sexual reproduction, chromosomes undergo a process called crossing over, where genetic material is exchanged between homologous chromosomes. This reshuffles existing alleles and creates new combinations of genes in offspring.

Answer 76

Recombination

Question 77

random fluctuation of allele frequencies within a population. It can occur due to chance events like sampling error (founder effect) or bottlenecks (sudden population decline).

Answer 77

Genetic Drift

Question 78

acts on the existing variations within a population, favoring individuals with traits that enhance their survival and reproduction in a specific environment. These individuals are more likely to pass on their advantageous traits to the next generation, leading to gradual adaptation of the population over time.

Answer 78

Natural Selection

Question 79

Humans can also exert selective pressure on populations through

Answer 79

Artificial Selection

Question 80

principle that describes a population in which allele frequencies remain constant over generations. This equilibrium state is reached when there are no evolutionary forces acting on the population (no selection, no migration, no mutations, and a large population size).

Answer 80

Hardy-Weinberg Equilibrium

Question 81

Mechanisms of Evolution

Answer 81

Mutation, Gene Flow, Recombination, Genetic Drift, Natural Selection, Artificial Selection, Hardy-Weinberg Equilibrium