Evolution and Behavior MCQ Quiz - Objective Question with Answer for Evolution and Behavior - Download Free PDF

The correct answer is A: False, B: True, C: False, D: True

Concept:

• Evolution by natural selection is a fundamental mechanism driving the diversity of life. It favors traits that enhance survival and reproduction in a given environment.
• Adaptation refers to the process where organisms evolve traits that allow them to function better in their environment. However, adaptation does not imply perfection, and various constraints can influence the process.
• The traits we see today are shaped by past environments, and adaptation is not limited to the current environment but reflects historical interactions with selection pressures.
• Natural selection is one of many processes influencing evolution. Other mechanisms, like genetic drift, gene flow, and mutation, also play roles in shaping traits.

Explanation:

• A: False: Adaptation does not imply that organisms are perfectly matched to their current environment. Evolution works on available genetic variation and may lead to traits that are "good enough" rather than perfect. Additionally, environments can change faster than evolution can adapt organisms to them, leaving mismatches.
• B: True: Adaptive traits are shaped by natural selection acting on past environments. Evolution is influenced by historical selection pressures, meaning traits that were advantageous in the past may still persist even if the current environment has changed.
• C: False: While natural selection is a primary mechanism driving adaptation, it is not the only process. Other evolutionary processes, such as genetic drift (random changes in allele frequencies) and gene flow (movement of genes across populations), can also influence traits and their prevalence in populations.
• D: True: Adaptation to current environments may be constrained by adaptations to past environments. For example, traits that evolved for past environments may limit the ability to adapt to new environments, creating evolutionary "trade-offs."

The correct answer is X = 7.0, Y = 4.0, Z = 7.0

Concept:

• Phylogenetic diversity (PD) measures the total branch lengths of a phylogenetic tree that connects all the species present in a community. It provides insight into the evolutionary relationships among species within a community.
• Phylogenetic diversity (PD) for a community is calculated as the sum of the branch lengths of the phylogenetic tree that are spanned by the species present in that community.
• The absence (0) and presence (1) of species in the communities X, Y, and Z are provided in the table alongside the phylogeny. 

Explanation:

• Community X: Species present in Community X (from the table where X = 1): Species 1, Species 6, Species 7.
• Community Y: Similarly, using the presence of species in Y and summing the branch lengths that connect them, the total PD is calculated to be 4.0.
• Community Z: Using the species present in Z and their corresponding branch lengths, the total PD is calculated to be 7.0.

The correct answer is Polyandry: Q, male, P, female; Polyandry: P, male, Q, female

Concept:

Mating systems in birds are classified based on the distribution of reproductive success between males and females. Key mating systems include monogamy, polygyny, and polyandry.

• Polygyny: In this system, males have multiple mates, resulting in higher reproductive success for males (P) compared to females (Q).
• Polyandry: In this system, females have multiple mates, leading to higher reproductive success for females (P) compared to males (Q).
• The operational sex ratio (OSR), which is the ratio of sexually active males to females, is assumed to be 1:1 in this study.

Explanation:

• In Polygyny, the male mates with multiple females. So, the male should have the highly variable and high number of matings. This suggests P = female, Q = male. (Since Q shows higher peak matings).
• In Polyandry, the female mates with multiple males. So, the female should have the highly variable and high number of matings. This suggests P = male, Q = female. (Since Q shows higher peak matings).

The correct answer is Yes, because 3.0 genetic units are gained and 2.0 genetic units are lost.

Concept:

• Hamilton's Rule: Hamilton's rule is a principle in evolutionary biology that explains when altruistic behaviors (e.g., helping others at a cost to oneself) can evolve. The rule states that an altruistic act will be favored by natural selection if the genetic benefit to relatives outweighs the genetic cost to the altruist. Mathematically, the rule is expressed as rB > C, where:
  • r: Coefficient of relatedness between the altruist and the recipient.
  • B: Benefit to the recipient (in terms of genetic units).
  • C: Cost to the altruist (in terms of genetic units).
• In many eusocial insects like paper wasps, workers often forgo their own reproduction to help raise their siblings. This behavior can be explained using Hamilton's rule and the concept of inclusive fitness, where an individual's fitness includes the reproductive success of their relatives.

Explanation:

The worker wasp has two options:

1. Produce 4 offspring of her own.
2. Help raise 4 full-sisters instead.

Relatedness:

• A worker wasp is related to her own offspring by r = 0.5 (50% shared genes).
• A worker wasp is related to her full-sisters by r = 0.75 (75% shared genes, due to haplodiploidy in hymenopteran insects like wasps).

Calculating Genetic Units:

• If the worker produces 4 offspring, the genetic contribution is:
  • 4 offspring × r (0.5) = 2.0 genetic units.
• If the worker helps raise 4 full-sisters, the genetic contribution is:
  • 4 full-sisters × r (0.75) = 3.0 genetic units.
• Cost vs. Benefit:
  • Cost (C): The worker loses the opportunity to produce her own 4 offspring, which would result in 2.0 genetic units.
  • Benefit (B): The worker gains 3.0 genetic units by helping raise her full-sisters.
  • Using Hamilton's rule (rB > C):
    • 3.0 (gain) > 2.0 (loss).

Since the benefit outweighs the cost, this altruistic behavior is favored by natural selection.

The correct answer is 5.76

Explanation:

• The Hardy-Weinberg equilibrium principle states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences.

To calculate the expected genotype frequencies under Hardy-Weinberg equilibrium, we use the formula:

• Frequency of genotype = (frequency of allele 1) × (frequency of allele 2).
• Here, "AaBb" is a genotype that involves heterozygosity for both genes (A and B). For heterozygous genotypes, the calculation combines probabilities of each allele pairing.
• Given Data:
  • Frequency of allele 'a' = 0.2
  • Frequency of allele 'A' = 1 - 0.2 = 0.8
  • Frequency of allele 'b' = 0.1
  • Frequency of allele 'B' = 1 - 0.1 = 0.9
• Genotype AaBb:
  • Since AaBb involves heterozygosity (one dominant and one recessive allele for each gene), the probability can be calculated as follows:
  • Frequency of Aa = 2 × (frequency of A × frequency of a) = 2 × (0.8 × 0.2) = 0.32
  • Frequency of Bb = 2 × (frequency of B × frequency of b) = 2 × (0.9 × 0.1) = 0.18
  • Frequency of AaBb = Frequency of Aa × Frequency of Bb = 0.32 × 0.18 = 0.0576
  • Expected genotype population with AaBb = 5.76%

The correct answer is Option 1 i.e.64

Concept:

• Hardy Weinberg's principle relates genotypic frequency and allelic frequency in a population that is mating randomly. 
• Hardy Weinberg equilibrium states that in the absence of external disruption, genotypic frequencies in a population remain stable across generations.
• Hardy Weinberg equation is given by 
• \(p^2 + 2pq + q^2 = 1 \)
• Here, the p and q represent the frequency of the dominant allele and recessive allele, and \(p^2, 2pq\) and \(q^2\)represent the frequency of homozygous dominant, heterozygous and homozygous recessive.
• Random mating, infinite population size,  no mutation, no gene flow, and no selection are assumptions of Hardy-Weinberg equilibrium.

Explanation:

• Frequency of homozygous recessive phenotype \(q^2 = 0.04 \)
• Then the frequency of recessive allele = q=0.2
• According to the Hardy-Weinberg equilibrium, \(p+q=1\)
• Now, the frequency of the dominant allele (p) is:

  \(\begin {equation} \begin {split} p &= 1-q \\&= 1-0.2 \\&= 0.8\\ \end {split} \end {equation}\)

• Frequency of homozygous dominant phenotype \(=p^2\)
• Therefore, the frequency of homozygous dominant individuals in the population is:

\(\begin{equation} \begin {split} p^2 &= 0.8 \times 0.8 \\ p^2 &= 0.64 \end {split} \end {equation} \)

• The percentage of individuals homozygous for the dominant allele is 64%.

Hence, the correct answer is Option 1.

The correct answer is Option 4 i.e. Alveolates and amoeba belong to same super group.

Concept:

• Eukaryotes are divided into 5-6 supergroups based on the phylogenomic analysis where each subgroup contains organisms for which there is enough evidence that they formed a monophyletic group. 
• Five to six super-groups were originally proposed depending on the fact whether Opisthokonta and Amoebozoa subgroups were united in a single large group called Unikonta. 

Supergroups - 

1. Opisthokonta - 
   • It includes fungi, animals and several protist lineages which are either closely related to fungi or animals.
   • Flagellated cell is the one most common characteristics of opisthokonts.
   • Opisthokonts are split into two major groups: Holomycota (kingdom Fungi) and Holozoa (kingdom Animalia).
2. Amoebozoa - 
   • It includes amoeboid life forms with lobose pseudopodia, some filose amoebae, various slime-mould, and some flagellates.
   • Pseudopodia is the common characteristic that extends like tubes or flat lobes.
   • Organisms of this super-group can be free-living or parasites. 
3. Excavata - 
   • It was originally proposed by Simpson and Patterson in 1999 and later by Thomas Cavalier-Smith in 2002 as a formal taxon.
   • Members of this super-group have distinctive morphology found in the flagellated protists like feeding groove form, associated cytoskeleton, etc. 
   • This group includes heterotrophic predators, parasites and photosynthetic species.
   • Its sub-groups are - diplomonads, parabasalids and euglenozoans.
4. Archaeplastidia - 
   • It includes green algae and land plants, red algae and glaucophyte algae. 
   • The characteristic feature of members of this supergroup is the presence of chloroplast.
   • The main evidence in the favour of Archaeplastidia forming a monophyletic group comes from genetic studies which indicate a single origin of plastids i.e., endosymbiotic theory of plastid origin.  
5. Chromalveolata - 
   • The ancestors of supergroup chromalveolata are believed to have resulted from the second endosymbiotic event. 
   • The ancestors of Chromalveolata have engulfed a photosynthetic red algae cell, which itself had evolved chloroplast from the endosymbiotic relationship with photosynthetic prokaryotes. 
   • Its sub-group includes alveolates and stramenopiles. 
6. Rhizaria - 
   • It is the most recently added supergroup.
   • The characteristic feature of members of Rhizaria is the presence of needle-like pseudopodia. 
   • Its sub-group includes Forams and Radiolarians.

Explanation:

Option 1: Fungi and animals are more closely related to each other than either group is to plants. 

• Fungi and animals are classified under the same supergroup Opisthokonta. 
• While land plants are classified under the supergroup Archeaplastid.
• So, fungi and animals are more closely related to one another than plants.
• Hence, this is a true statement.

Option 2: Amoebozoa and opisthokonts are unikonts.

• Amoebozoa and Opisthokonts are grouped under one monophyletic group called unikonts. 
• Unikonts include eukaryotic cells with a single flagellum, at least ancestrally. 
• Some research suggests that a unikont was the ancestor of Opisthokonts and Amoebozoa while a bikont was an ancestor of other eukaryotic lineages i.e., Archaeplastida, Excavata, Rhizaria, and chromalveolata.
• Hence, this is a true statement.

Option 3: Land plants and green algae belong to Archaeplastida.

• Archarplastidia includes green algae and land plants, red algae, and glaucophyte algae.
• Hence, this is a true statement.

Option 4: Alveolates and Amoeba belong to same super group. 

• Alveolates belong to the supergroup Chromalveolata while Amoeba belongs to the supergroup Amoebozoa.
• Hence, this is a false statement. 

Conclusion:-Hence, the correct answer is Option 4. 

The correct answer is A,B and C

Explanation:

Phylogenetic trees are graphical representations that depict the evolutionary relationships among various biological species or entities based on similarities and differences in their physical and/or genetic characteristics. 

1. A. Relatedness among different populations, species, or genera: This statement is correct. Phylogenetic trees illustrate the relatedness or evolutionary relationships among different groups. This is one of the primary purposes of phylogenetic analysis.
2. B. Similarity in characters among different populations, species, or genera: This statement is correct. While similarities in characters (morphological, genetic, etc.) are used to construct phylogenetic trees, the trees themselves primarily represent evolutionary relationships and relatedness rather than just similarity.
3. C. Common ancestry among different populations, species, or genera: This statement is correct. Phylogenetic trees are used to infer common ancestry. By examining the branching patterns, one can determine the most recent common ancestors of the groups being studied.
4. D. Functional significance of traits in populations, species, or genera: This statement is incorrect. While phylogenetic trees can provide some insights into evolutionary processes that might affect functional traits, they are not primarily used to assess the functional significance of traits. Functional significance is more directly examined through other methods, such as comparative physiology or ecology.

Conclusion
Based on the analysis, the correct statements about the utility of phylogenetic trees are: A and C

The correct answer is Triassic.

Explanation:

The Triassic period (around 252 to 201 million years ago) is known for several important evolutionary and geological events:

1. Marine Diversity: After the Permian-Triassic extinction event (the largest mass extinction in Earth's history), the early Triassic period saw a gradual recovery and increase in marine diversity. New groups of marine reptiles, like ichthyosaurs and plesiosaurs, appeared during this time.

2. Dominance of Gymnosperms: Gymnosperms, such as cycads and conifers, became the dominant plant group during the Triassic. These plants thrived in the drier climates that characterized much of the period.

3. Diversification of Synapsids: Synapsids (including ancestors of mammals) diversified during the Triassic period. The first mammal-like forms (known as therapsids) evolved during this time, laying the foundation for the later evolution of true mammals.

4. Emergence of Dinosaurs: The Triassic also saw the rise of archosaurs, a group that includes dinosaurs. The earliest known dinosaurs, such as Eoraptor and Herrerasaurus, appeared in the late Triassic.

Why the other periods are incorrect:

• Cretaceous: The Cretaceous (145 to 66 million years ago) saw the diversification of flowering plants and the dominance of dinosaurs, but it came after the Triassic.
• Jurassic: The Jurassic (201 to 145 million years ago) is known for the flourishing of dinosaurs and conifers, but the emergence of these forms occurred earlier in the Triassic.
• Carboniferous: The Carboniferous (359 to 299 million years ago) is known for vast swampy forests and the evolution of amphibians and early reptiles, but the events mentioned (marine diversity, synapsids, dinosaurs) occurred later in the Triassic.

Thus, the Triassic period is when these key evolutionary events occurred.

The correct answer is Indohyus.

Explanation:

Indohyus is an extinct genus of a small deer-like, herbivorous animal from the family Raoellidae, which lived about 48 million years ago. In 2007, scientists discovered fossils of Indohyus in the Kashmir region of India, and these fossils provided critical evidence linking it to cetaceans (the group that includes modern whales, dolphins, and porpoises).

Key evidence suggesting that Indohyus was a close terrestrial ancestor of whales includes:

• Bone structure: It had dense bones, similar to those seen in modern aquatic animals that spend a lot of time in water, suggesting it was semi-aquatic.
• Ear structure: The structure of the ear bones in Indohyus resembled that of modern whales, indicating an evolutionary relationship.
• Lifestyle: It is believed to have waded in water and perhaps fed on aquatic plants, which shows an adaptation to aquatic environments, a key transition towards full aquatic life seen in modern whales.

This discovery was significant because it helped scientists understand the evolutionary shift from land-dwelling mammals to fully aquatic cetaceans.

The other options you mentioned are unrelated to the ancestry of whales:

• Jainosaurus: A genus of titanosaurs, a type of herbivorous dinosaur.
• Rajasaurus: A carnivorous dinosaur from India.
• Indosuchus: A genus of theropod dinosaurs, also from India.

Thus, the correct fossil that is considered a close ancestor of whales is Indohyus.

The correct answer is Option 1 i.e.A ‐ IV, B ‐ III, C ‐ I, D ‐ II

Concept:  

• A cell or an organism's behavioural response to outside stimuli is called taxis.
• It is different from kinesis which is a behavioural reaction that results in the movement of organisms in response to an external stimulus.  
• In the case of kinesis, the movement is random or not directionally oriented, whereas in the case of taxis the movement is directionally oriented.
• The movement could be favourable or unfavourable.
• When an organism or cell is travelling toward the source of stimulus, this is referred to as a positive taxis (attraction).
• When a cell or an organism is travelling away from the source of stimulation, this is referred to as a negative taxis (repulsion).
• Taxis also differ from tropism, an automatic, either positive or negative, orienting response to a stimulus source.
• Different types of taxis movement are involved. 

Important Points

• Menotaxis -
  • It is a movement where the organism is maintaining a constant angle to a stimulus.
  • Silk moth flies moving in the direction perpendicular to the wind (stimuli) in order to locate the scent trial is an example of Menotaxis. 
• Magnetotaxis - 
  • ​It is the passive orientation and active movement of organisms in the response to the magnetic field.
  • The movement of bacteria in the response to the magnetic field and burrowing is an example of magnetotaxis.
• Mnemotaxis -
  • It is also known as 'memory response', that is navigation with the use of landmarks.
  • The girl using landmarks to travel to her school is an example of Mnemotaxis. 
• Klinotaxis -
  • It is the wavering side-by-side motion of a part of the body(head) or all of the body, as the organism is moving in the direction of the stimulus.
  • The movement of planaria towards the higher concentration of food by comparing the stimuli is an example of klinotaxis.

Hence, the correct answer is Option 1.

The correct answer is Option 2 i.e. D-C-B-A

Concept:

• The geological time scale is a chronological sequence of evolutionary and geological events spanning the physical formation and development of the Earth.
• In essence, the geological time scale is the Earth's history that is been recorded and represented in the rock strata of the Earth.
• The geological time scale is divided into descending order of duration- eon, era, period, epoch and age.
• The name of division is mainly based on the fossil evidences and principle of carbon dating and most of the boundaries correspond with the origination of extinction of particular kinds of fossils.

Explanation:

• Cambrian period extended from 541 million to 485.4 million years ago.
• Jurassic period extended from 199.6 million to 145.5 million years ago.
• Cretaceous period extended from 145.5 million years to 66 million years ago.
• Quaternary period extended from 2.58 million years to today.

So, the correct order from earlier to recent is Cambrian - Jurassic - Cretaceous - Quaternary. 

Hence, the correct answer is D - C - B - A.​​

The correct answer is Option 4 i.e.Living fossils are organisms that have remained unchanged for millions of years. 

Concept:

• An organism that has stayed largely the same over millions of years with no or few close surviving relatives is considered as a living fossil.
•  The phrase "living fossil" was first used by English biologist Charles Darwin in 1859 to describe a species or group of animals that have altered very little over time as to offer insight into older, now-extinct forms of life.
• Charles Darwin was of the opinion that these organisms are still evolving and these species have adapted to their environmental controls, thereby reaching a peak of competence in environments which leads to the constant strengthening of certain physical characteristics.
• Thus these physical characteristics are still prevalent even after millions of years. 
• Example of living fossils :
  • Unicellular - Cyanobacteria, Amoeba and Protozoa
  • Multicellular - Coelacanth,  Goblin shark, Opossum, Lamprey and Platypus

Explanation:

• Option 1: Living fossils are impressions of extant organisms in old rocks.
  • ​Impression is the 2-D imprint of an organism and it does not contain any organic material.
  • It is a clue left as to the activity performed by the organism. 
  • Some examples of impressions are the footprints, remains of tunnels fossilized excreta of organisms, etc.
  • Hence, this is an incorrect option.
• Option 2: Living fossils show high morphological divergence from fossil records.
  • ​Living fossils closely resemble their fossilized relatives, so they do not show any morphological divergence.
  • This is an incorrect option.
• Option 3: Living fossils are always an evolutionary link between two classes of organisms.
  • ​Connecting link is the organism are the evolutionary link between two organisms as they share characteristics from both classes.
  • Hence, this is an incorrect option.
• Option 4: Living fossils are organisms that have remained unchanged for millions of years. 
  • Living fossils are organisms that have existed for millions of years and they have still remained mostly unchanged.
  • For example, Horseshoe crab is a living fossil as it has remained unchanged for 445 million years. 
  • Even today horseshoe crabs are living and we also find fossils of some species of horseshoe crab some 445 million years ago. 
  • Hence, this is the correct option.

Hence, the correct answer is Option 4.

The correct answer is Option 3

Explanation:

Artiodactyls are a group of even-toed ungulates, which include animals like pigs, hippos, camels, and cows. Molecular and genetic studies have shown that whales (cetaceans) are most closely related to a subgroup of artiodactyls, particularly hippos.

• Tree 1: Shows whales sharing a recent ancestor with camels and horses. This is incorrect because whales are not most closely related to camels or horses.
• Tree 2: Shows whales sharing a common ancestor with pigs and horses, while hippos are distantly related. This is also incorrect because molecular data place whales closer to hippos than to pigs or horses.
• Tree 3: Shows whales sharing a most recent common ancestor with hippos, with both whales and hippos branching off from a common ancestor they share with pigs. This is the correct representation, as it aligns with the molecular evidence.
• Tree 4: Shows whales branching off from a common ancestor shared with pigs, hippos, and camels. While this includes relevant species, it does not accurately reflect the specific close relationship between whales and hippos.

The correct answer is Genotype frequencies: 0.64 WW 0.32 Ww and 0.04 Ww Allele Frequencies W-0.8 and w-0.2

Explanation:
The total population size is given as 500 individuals.

Given genotypes:

• WW: 320 individuals
• Ww: 160 individuals
• ww: 20 individuals

Genotype frequency is calculated as the number of individuals with the genotype divided by the total population size.

• Frequency of WW (p²): Frequency of WW = no of WW individuals / Total no of indiviuals = 320/500= 0.64
• Frequency of Ww (2pq): No. of Ww individuals / Total no of individuals = 160/500= 0.32
• Frequency of ww (q²): No of ww individuals / Total no of individuals= 20/500= 0.04

Calculate the total number of each allele in the population. Each individual contributes two alleles.

Number of W alleles:

• From WW individuals: ( 320 X 2 = 640 )
• From Ww individuals: ( 160 X 1 = 160 )
• Total W = 640 + 160=800

Number of w alleles:

• From ww individuals: ( 20 X 2 = 40 )
• From Ww individuals: ( 160 X 1 = 160 )
• Total w = 40+160= 200

Next, calculate the total number of alleles in the population:

Total alleles in the population = 2 x (Number of individuals} = 2 x 500 = 1000 

Now, determine the allele frequencies:

• Frequency of W (p): 800/1000= 0.8
• Frequency of w (q): 200/1000 = 0.2

Summary
Genotype Frequencies:

• WW: 0.64
• Ww: 0.32
• ww: 0.04

Allele Frequencies:

• W: 0.8
• w: 0.2