Table of Contents
Evolutionary Biology 2020
1.a) Define Species.
Ans→ Species is a group of organisms that can interbreed and produce fertile offspring.
Example: Homo sapiens (Human)
b) Define mass extinction.
Ans→ A mass extinction is an event, where a large number of species become extinct over a relatively short geological time period.
c) What are coacervate particles?
Ans→ Coacervate particles are small, liquid droplets formed when certain molecules like protein aggregate or exhibit properties similar to cell membrane.
d) What is ‘Era’?
Ans→ Era is a long period of time that refers to a major division of geological time characterized by distinct patterns of evolution.
e) What do you mean by Hominin?
Ans→ Hominin is a group of evolutionary lineage of modern humans and their extinct ancestors, distinguished by upright posture and large brains.
f) Define mutation.
Ans→ Mutation is a permanent change in the DNA sequence of an organism may lead to genetic variation within the population.
g) What do you mean by ‘cline’?
Ans→ Cline is a gradual change in a characteristic of a species across. a geographical area, typically due to environmental factors.
h) According to the “endosymbiosis theory”, which cell organelles have an important role in the formation of the eukaryotic cell?
Ans→ Mitochondria and chloroplasts
ⅰ) Give the name of any two ancestors and relatives of modern human (fossil records).
Ans→ Homo neanderthalensis (Neanderthals) and Homo erectus
j) The K-T extinction marks the end of which era ?
Ans→ Mesozoic Era.
k) What is the importance of “Hardy-Weinberg principle?
Ans→ It provides a theoretical framework for understanding how allele frequencies remain stable in a population over time.
l) Give an example of Lamarck’s proposition of “Use and Disuse of Organs”.
Ans→ Lamarck proposed that giraffes stretched their necks to reach leaves of high trees and over time this stretching caused their necks to become longer.
m) What is ‘sexual selection’.
Ans→ Sexual selection refers to the process by which individuals of one sex(usually male) compete with each other or display certain traits to attract mates of the opposite sex (usually female).
n) Write down any two key characters of primate’
Ans→ (i) Forward facing eyes: Primates have eyes positioned at the front of their face which provide binocular vision.
(ii) Opposable thumbs: Primates possess thumbs that can move independently and oppose the other fingers.
o) What is ‘cladogram’?
Ans→ Cladogram is a branching diagram that shows the evolutionary relationship between different groups of organisms based on shared derived characteristics.
2.a) Write a short note on Molecular Clock?
Ans→ Molecular clock is a concept/hypothesis in evolutionary biology suggests that the rate of genetic mutations accumulates in a relatively constant manner over time. By comparing the genetic differences between species or population can estimate the time since their divergence from a common ancestor.
b) Distinguish between convergent and divergent evolution.
Ans→
c) Write the salient features of ‘RNA world-hypothesis.
Ans→ RNA World: Proposed that RNA molecules crucial for early life forms before DNA and proteins.
Evolutionary precursor: RNA may have served as a transitional molecule evolving into DNA for stability and protein for diverse functions
Act as Genetic material: RNA molecules can act as both genetic material and enzymes.
d) Write the salient features of Darwin’s theory of ‘Natural Selection’.
Ans→ Survival of the Fittest: Individuals which are fit are more likely to survive and reproduce, passing their traits to the next generation.
Natural Selection: Nature selected those individuals which are fittest.
Adaptation: Through natural selection, populations gradually become better adapted to their environment.
e) Distinguish between Allopatric and Sympatric speciation.
Ans→
f) What is ‘Bottleneck Effect’?
Ans→ Bottleneck effect refers to drastic/sharp reduction in the size of population due to sudden environment change, catastrophe or human activity, leading to loss of genetic diversity.
g) What are the main causes of ‘Heritable variation’?
Ans→ Mutation: Random changes in the DNA sequence of an organism, which can lead to new alleles and genetic diversity.
Genetic Recombination: During meiosis, genetic recombination between homologous chromosomes results in a new combination of alleles.
Gene flow: The movement of genes between populations through migration can introduce new allele causes variation.
h) Point out some important modifications that took place in the body of Hyracotherium (Eohippus) to make them large grazing and fast running animals (Eqqus).
Ans→ Increase in body size: Hyracotherium was a small sized animal evolved into larger sized Equus, facilitating efficient grazing and allowed speed and endurance.
Digit reduction: Equus went a reduction in the number of toes to a single functional toe (hoof) in Equus.
Limb elongation and strength: The limbs of Equus became elongated and strengthened enabling them to support the increased body weight and engage in fast running locomotion.
Evolutionary Biology 2021
1. a) Who gave the idea of Chemogeny?
Ans→ Alexander Oparin in 1920.
b) How does fitnessed related to Natural Selection?
Ans→ Fitness in the context of Natural selection refers to an organism’s ability to survive and reproduce in it’s environment.
c) Define adaptive radiation.
Ans→ Adaptive radiation is a process where a single ancestral species rapidly diversifies into multiple different species, each adapted to specific habitat.
d) Define convergent evolution.
Ans→ Convergent evolution is a when unrelated organisms independently evolve similar traits or characteristics due to similar environmental pressures.
e) What does the Natural theory of molecular evolution contend?
Ans→ Natural theory of molecular evolution suggests that genetic variation arises through random mutations and those variations that enhance an organism’s fitness are more likely to be passed onto future generations through natural selection.
f) What is heterozygous superiority?
Ans→ Heterozygous superiority refers to a situation where individuals with two different alleles for a particular gene (heterozygotes) have greater fitness compared to individuals with two identical alleles (homozygotes).
g) What is Sewall-Wright Effect?
Ans→ Sewall-Wright effect (shifting balance theory) proposes that genetic drift, selection and gene flow can work together to allow populations to explore and adapt to new environments over time.
h) Give an example of bottleneck effect.
Ans→ Northern elephant seals.
i) What is Epoch?
Ans→ Epoch refers to a distinct period of time characterized by occurence of important specific evolutionary events.
j) Define ‘Biological species’.
Ans→ Biological species is a group of organisms that can interbreed and produce fertile offspring and are reproductively isolated from other group.
k) Why is parsimony important in phylogenetic trees?
Ans→ Parsimony is important in phylogenetic trees to find the simplest explanation for evolutionary relationships to explain observed data.
l) Define Geologic time scale.
Ans→ Geologic time scale is a timeline that divides Earth’s history into distinct intervals based on major geological and biological events.
m) Which of the molecular study indicates the human evolution?
Ans→ Molecular Anthropology
n) What does the Hardy Weinberg law mean?
Ans→ Hardy Weinberg law is a principle in population genetics stating that allele frequencies in a population remain constant from generations in absence of evolutionary forces.
o) What is panmictic population?
Ans→ Panmictic population is one where individuals have an equal chance of mating with any other individual in the population without any restrictions.
2. Why does photosynthesis causes the largest extinctions?
Ans→ During the Great Oxygenation Event, photosynthetic organisms produce oxygen (O2) levels in atmosphere by photosynthesis, leading to a significant change in the composition of the atmosphere. It likely led to the death of many anaerobic organisms causing the largest extinction.
b) Explain Founder Effect with an example.
Ans→ The Founder effect occurs when a small group from a larger population establishes a new colony and establishes a new population in different geographical areas. Example: A small group of Amish population migrated to America, establishing isolated communities with limited gene flow.
c) Why fossils are important evidence for support evolution?
Ans→ Fossils are important evidence of organisms that lived in ancient times. It shows the transitional forms and evolutionary changes over time of that organism. Fossils supporting the theory of evolution by demonstrating the gradual development of life forms from common ancestors.
d) What are the main difference between Darwinism and Neo-Darwinism.
Ans→
e) Write down the sources of Genetic variation.
Ans→ (i) Mutation: Changes in the DNA sequence.
(ii) Genetic Recombination: Recombination of genetic material during meiosis.
(iⅲ) Gene flow: Movement of genes between populations through migration.
(iv) Sexual reproduction: Combination of genetic material from
two individuals during fertilization.
f) What is convergent evolution?
Ans→ Convergent evolution is when unrelated species independently evolve similar traits or characteristics due to adapting similar environmental pressures or niches.
Example: Flippers of dolphins and penguins ; Wings of birds and butterflies.
g) What is Biogeny in evolution?
Ans→ Biogeny, also known as recapitulation theory ‘ontogeny recapitulates phylogeny’ suggests the study of the development of living organisms is related to their evolutionary history or phylogeny.
h) What is allele frequency?
Ans→ Allele frequency refers to the proportion of a particular allele within a population’s gene pool, representing how common that allele is in the population.
Evolutionary Biology 2022
1.a) What evidence is there for RNA world?
Ans→ RNA acts as both genetic material and catalytic functions, predating the emergence of DNA and proteins.
b) Mention two features that distinguish hominidae from other primates.
Ans→ (i) Bipedalism: Hominids are characterized by habitual bipedal locomotion (walking on two legs) while primates walk on four legs.
(ii) Large brain size : Hominids have larger brains relative to their body size compared to other primates.
c) Why did horses evolve to have single-toed hooves?
Ans→ Horses evolve to single-toed hooves because for fast running, they require less energy to support and move compared to multiple toes.
d) what is the beginning of a phylogenetic tree called?
Ans→The beginning of a phylogenetic tree is called the root.
e) Define subspecies.
Ans→ A subspecies is a taxonomic rank below species, representing distinct populations within a species that have some differences in traits but can interbreed and produce fertile offspring.
f) How does migration affect genetic variation is a population?
Ans→ Migration of individuals between populations can introduce new alleles, facilitate gene flow, causing genetic differentiation and lead to genetic variation.
g) What do you mean by monophyletic phylogeny?
Ans→ Monophyletic phylogeny refers to a tree diagram or classification system where all the organisms share a single common ancestor and include all its descendants.
h) What are the main causes (two) of mass extinctions.
Ans→ (1) Catastrophic Event: Events such as asteroid impact, Volcanic eruption causes of mass extinction of numerous specie
(ⅱ) Disease outbreak: Epidemic diseases can cause mass extinction of a population.
i) What is the hypothesis of endosymbiosis?
Ans→ Hypothesis of endosymbiosis suggests that eukaryotic cells evolved from the symbiotic relationship between different types of prokaryotic cells leading to the formation of new cell organelles like mitochondria and chloroplast within eukaryotic cells.
j) What is one advantage of using parsimony in phylogenetics?
Ans→ Parsimony helps in finding the simplest explanation for evolutionary relationships by minimizing the number of evolutionary changes required to explain observed data.
k) What is gene pool?
Ans→ Gene pool refers to a complete set of genes and alleles present in a population or species.
l) What is the purpose of a molecular clock in evolutionary biology?
Ans→ The purpose of a molecular clock in evolutionary biology is to estimate the timing of evolutionary events by measuring the rate of genetic change over time.
m) Define mullerian mimicry.
Ans→ Mullerian mimicry is an evolutionary phenomenon where multiple harmful or unpalatable species resemble each other, gaining protection through shared warning signals.
n) What does the Hardy Weinberg Law state?
Ans→ Hardy Weinberg law states that allele frequencies in a population remain constant from generations in absence of evolutionary forces.
o) How Neo Darwinism natural selection operates?
Ans→ New Darwinism natural selection explaining evolution through genetic variation, mutation, recombinal, and differential reproductive success.
2. a) How females choose their mates (In Bird)?
Ans→ Females often select mates based on physical traits such as bright plumage colour, size and overall health. Female birds choose on the performance or songs or courtship displayed by males. They choose mates based on the quality of their territory, food or safety from predators.
b) Define maximum parsimony.
Ans→ Maximum parsimony is a principle of phylogenetics that favours the construction of evolutionary trees by minimizing the number of evolutionary changes on mutations required to explain differences among species.
c) Distinguish between Cladogenesis and Anagenesis.
Ans→
d) What do you mean by geological time scale? What era are we currently in?
Ans→ The geological time scale is a framework used by scientists to divide Earth’s history used by into distinct intervals based on significant geological and biological events.
We are currently in the Cenozoic era.
e) What is K-T extinction?
Ans→ The K-T extinction or Cretaceous-Paleogene extinction was a mass extinction event occurred approximately 66 mya results in the extinction of dinosaurs and many species likely caused by an asteroid impact.
f) What do you mean by ‘eugenics’?
Ans→ Eugenics is a social and political movement aimed at improving the genetic quality of a population by controlling reproduction, through selective breeding to promote certain traits, or characteristics.
g) What is adaptive radiation and example?
Ans→ Adaptive radiation is a process where a single ancestral species rapidly diversifies into multiple different species, each adapted to specific habitats.
Example: Finches of the Galapagos Island.
h) What is isolation mechanism? What are the 3 types of isolating mechanisms that lead to speciation?
Ans→ Isolation mechanisms are barriers that prevent species from interbreeding, maintaining reproductive isolation.
(i) Geographical Isolation (ii) Behavioral Isolation and (iii) Ecological Isolation / Temporal Isolation are the 3 types of isolating mechanisms.
Evolutionary Biology 2023
1. a) Define allopatric speciation?
Ans→ Allopatric speciation occurs when a population is separated geographically, leading to the formation of new species due to reproductive isolation over time.
b) Differentiate between convergent and divergent evolution.
Ans–>
c) What is cladogram?
Ans→ Cladogram is a branching diagram that shows the evolutionary relationship between different groups of organisms based on shared derived characteristics.
d) Which is the largest “Geological time’ unit?
Ans→ Eons
e) What is bottleneck phenomenon?
Ans→ Bottleneck effect refers to drastic/sharp reduction in the size of population due to sudden environment change, catastrophe or human activity, leading to loss of genetic diversity.
f) What is the concept of fitness is natural selection and evolution.
Ans→ Fitness in the context of Natural selection refers to an organism’s ability to survive and reproduce in it’s environment.
g) Define allele frequency.
Ans→ Allele frequency refers to the proportion of a particular allele within a population’s gene pool, representing how common that allele is in the population.
h) What is meant by the founder effect?
Ans→ The Founder effect occurs when a small group from a larger population establishes a new colony and establishes a new population in different geographical areas.
i) What is phylogenetic tree?
Ans→ A phylogenetic tree to a diagram illustrating the evolutionary among a group of organisms, showing their common ancestry and branching patterns over time.
j) Define cline.
Ans→ Cline is a gradual change in a characteristic of a species across. a geographical area, typically due to environmental factors.
k) Explain chemogeny.
Ans→ Chemogeny is a theory of chemical evolution that depends on the chemical reactions and formation of substances on the basis of chemical reaction. The theory states that life occurs as a result of evolution of inorganic matter.
l) What is the difference between immigrants and migrants?
Ans→ Immigrants specifically refers to people who move permanently to a new country or region to settle there. Where migrants refers to people who move from one place to another. In summary, all immigrants are migrants but not all migrants are immigrants.
m) What organisms went extinct during “K-T’extinction”?
Ans→ Reptiles (Dinosaurs)
n) How has the atmosphere’s molecular oxygen become Abundant on earth?
Ans→ The abundance of molecular O₂ in earth’s atmosphere is primarily attributed to the process of photosynthesis carried out by early photosynthetic bacteria and later by plants.
o) What is co-evolution?
Ans→ Co evolution refers to the reciprocal influence of two or more species on each other’s evolution results in adaptation in one species in response to adaptations in one species in response to adaptations in another species leading close relationships.
2.a) What do you mean by the molecular clock and state its importance?
Ans→ Molecular clock is a concept that proposes the genetic mutations accumulate at a relatively constant rate over time in the DNA or protein sequences of organisms.
Significance: It helps in estimating the timing of evolutionary events, such as when species diverged from common ancestors by analysing the genetic differences between them.
b) Why do scientists think “RNA’ came first on earth?
Ans→ RNA is simpler in structure compared to DNA, suggesting it could have arisen in early earth conditions. RNA can both store genetic information and catalyse chemical reactions. RNA’s building block, nucleotides can be synthesised under prebiotic conditions, meaning they could have formed naturally on early Earth. That’s why scientists think ‘RNA’ came first on earth.
c) Discuss the isolating mechanisms in the evolution process.
Ans→ Isolating mechanisms in evolution prevent gene flow between populations leading to speciation. They include geographical barriers (like mountains), ecological differences (habitat), behavioural changes and genetic incompatibility (chromosomal rearrangement).These mechanisms promote the divergence of populations and the formation of new species.
d) What are polytypic species?
Ans→ Polytypic species are the species is traits across different geographic regions who displays variations or habitats but can still interbreed and produce offspring, considered as the same species.
Example: Eastern Gray Squirrel (Sciurus carolinensis)
e) What are the mayon evolutionary steps from ali hat Australopithecus to Homo sapiens?
Ans→ (i) Australopithecus (ii) Homo habilis (iii) Homo erectus (iv) Homo neanderthalensis (v) Homo sapiens.
f) What evidence strengthens the hypothesis that mitochondria were aerobic prokaryotes?
Ans→ The endosymbiotic theory proposes that mitochondria were once free living prokaryotic organisms that were engulfed by ancestral eukaryotic cells. Mitochondria share a similar structure, replication mechanism with bacteria. Mitochondrial DNA (mt DNA) is more closely related to bacterial DNA than eukaryotic nuclear DNA.
g) What are the important evolutionary adaptations (characters) of a horse?
Ans→ (i) Digit reduction: Over time, horses evolved, from ancestors with multiple toes to a single function toe (hoof).
(ii) Increase in size: Increase in size of limb, body to facilitate swift running.
(iii) Adaptations for Grazing: Their long necks with flexible lips allow horses to efficiently graze on grass.
h) Contrast random and assortive mating.
Ans→ Random mating occurs when individuals in a population mate with each other without any preference for specific traits, resulting in offspring with random combination.
Assortive mating involves individuals selecting mates based on specific traits leading to offspring with similar phenotypes.
2 thoughts on “Evolutionary Biology PYQ Shorts”