Question
In a natural classification, what do all members of a genus have in common?
A. They all have the same binomial name.
B. They all belong to the same species.
C. They can freely interbreed to produce fertile offspring.
D. They have all evolved from the same common ancestor
▶️Answer/Explanation
Answer: D. They have all evolved from the same common ancestor
Explanation:
In natural classification, organisms are grouped based on their evolutionary relationships. A genus is a group of species that are closely related because they share a common ancestor. Each species within a genus has a unique binomial name, but the genus name is the same for all species in that group.
Evaluation of Each Option:
A. Incorrect – Members of a genus have the same genus name but different species names, so their full binomial names are different.
B. Incorrect – A genus includes multiple species, not just one species.
C. Incorrect – Different species in the same genus usually cannot interbreed freely to produce fertile offspring.
D. Correct – All members of a genus have evolved from the same common ancestor, which is why they share many characteristics.
Question
A short sequence of amino acids (represented by letters) in cytochrome $c$ is shown for six vertebrates. Letters in bold indicate identical amino acids for all species.
Which statement refers to this section of cytochrome c?
A. The DNA base sequences for human and rhesus monkey are different.
B. The most DNA base changes are between humans and snapping turtles.
C. The largest number of amino acid differences is two.
D. The amino acid at position 32 is the most variable.
▶️Answer/Explanation
Answer: D. The amino acid at position 32 is the most variable.
Explanation:
Amino acid sequences are determined by DNA. If the amino acid sequence is shown and some letters are in bold, it means those amino acids are identical in all six species. To answer the question, we need to focus on amino acid variability, not DNA.
Evaluation of Each Option:
A. Incorrect – The question is about amino acid sequences, not DNA base differences. Even if DNA differs slightly, the amino acid may stay the same due to the genetic code.
B. Incorrect – This option refers to DNA base changes, but the question only shows amino acid sequences. We can’t directly count DNA changes from amino acid data.
C. Incorrect – If the sequence shows more than two amino acid differences between species, this can’t be true. We’d need to count the actual differences.
D. Correct – If the amino acid at position 32 is different in more species than any other position, then it is the most variable. This is something that can be seen directly in the sequence.
The Atlantic cod (Gadus callarias) is a fish which lays about 5 000 000 eggs in its lifetime. On average, only two of these eggs survive to become adult cod. How does this promote evolution?
A. All offspring are genetically identical, so become better adapted.
B. Laying many eggs provides food for other species to survive and become better adapted.
C. Some young cod change to become adapted to the environment and survive and pass on their genes.
D. Offspring with favourable variations survive and pass on their genes.
Answer/Explanation
Answer: D. Offspring with favourable variations survive and pass on their genes
Explanation:
Evolution happens through natural selection. When many offspring are produced, there’s a higher chance for genetic variation among them. Only the ones best suited to the environment survive, reproduce, and pass on their favourable traits. Over generations, this leads to a better-adapted population.
Evaluation of Each Option:
A. Incorrect – Offspring are not genetically identical. There is variation due to sexual reproduction and mutation, which is key to evolution.
B. Incorrect – While many eggs may be eaten, this does not directly promote evolution in cod. It benefits predators, not the evolution of the cod species.
C. Incorrect – Individuals do not change themselves to adapt. Adaptation happens across generations through selection of favourable traits.
D. Correct – Some offspring have favourable genetic traits, survive, and pass those traits on. This is natural selection, the main driver of evolution.
What characteristics describe homologous structures?
A. They have the same ancestral origin but may have different functions.
B. They have the same ancestral origin and always have the same function.
C. They have different ancestral origins and may have different functions.
D. They have different ancestral origins but always have the same function.
Answer/Explanation
Answer: A. They have the same ancestral origin but may have different functions.
Explanation:
Homologous structures are body parts in different species that come from the same ancestral origin, even if they have different functions now. For example, the forelimbs of humans, cats, whales, and bats all have the same basic bone structure, but are used for different purposes (grasping, walking, swimming, flying).
Evaluation of Each Option:
A. Correct – Homologous structures come from the same ancestor, but they can have different functions in different organisms.
B. Incorrect – While they have the same origin, homologous structures do not always have the same function.
C. Incorrect – Homologous structures have the same, not different, ancestral origin.
D. Incorrect – This describes analogous structures, not homologous ones. Analogous structures have different origins but similar functions (like bird wings and insect wings).
Which of the following are used as evidence for evolution?
I. Homologous structures
II. Selective breeding of domesticated animals
III. Overproduction of offspring
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
Answer/Explanation
Answer: A. I and II only
Explanation:
Evidence for evolution includes observable features that support species change over time. Mechanisms like overproduction explain how evolution works but are not direct evidence.
Evaluation of options:
I. Homologous structures – Direct evidence (show shared ancestry).
II. Selective breeding – Direct evidence (shows species can change over generations).
III. Overproduction of offspring – Not direct evidence; it’s a mechanism of natural selection.
Question
What can lead to the emergence of analogous structures?
A. Divergent evolution from a recent common ancestor
B. Convergent evolution of unrelated species
C. Splits in the fundamental niche of a species
D. Splits in the realized niche of a species
▶️Answer/Explanation
Answer: B. Convergent evolution of unrelated species
Explanation:
Analogous structures are body parts in different species that have similar functions but different ancestral origins. They arise because unrelated species adapt to similar environments or lifestyles, a process called convergent evolution.
Evaluation of Each Option:
A. Incorrect – Divergent evolution happens when related species evolve different traits from a recent common ancestor, leading to homologous structures, not analogous ones.
B. Correct – Convergent evolution causes unrelated species to develop similar features independently, producing analogous structures.
C. Incorrect – Splits in the fundamental niche relate to how species use resources but do not explain the emergence of analogous structures.
D. Incorrect – Splits in the realized niche also relate to ecological resource use, not the origin of analogous structures.
Question
Scientists studying ground finches (Geospiza fortis) on the island of Daphne Major in Galapagos found great differences in the shapes of the beaks.
What is the explanation for this variation in beak shape between the birds?
A. Ground finches grow larger beaks if there is competition for food.
B. They belong to different species.
C. They are adapted for different diets.
D. The more a beak is used by a ground finch, the larger it becomes.
▶️Answer/Explanation
Answer: C. They are adapted for different diets.
Explanation:
Variation in traits like beak shape within a species often happens because individuals are adapted to different environments or diets. This means natural selection favors different beak shapes depending on the type of food available, helping finches survive and reproduce.
Evaluation of Each Option:
A. Incorrect – Beak size does not grow larger simply because of competition; it’s determined genetically, not by use.
B. Incorrect – The finches belong to the same species (Geospiza fortis), but show variation within the species.
C. Correct – Different beak shapes help finches eat different types of food, showing adaptation to diet.
D. Incorrect – Beak size does not change from use; it is inherited and shaped by natural selection over generations.
Question
Which factor(s) would favour evolution by natural selection?
I. Long lifespans
II. Favourable characteristics acquired by individuals during their lifetime
III. Variation within a species
A. II only
B. III only
C. I and II
D. I and III
▶️Answer/Explanation
Answer: B. III only
Explanation:
Natural selection works when there is variation within a species, and individuals with traits that give them an advantage survive and reproduce. Traits acquired during an individual’s life are not inherited, so they do not drive evolution. Lifespan alone does not directly favour natural selection.
Evaluation of Each Statement:
I. Long lifespans – Incorrect; lifespan length does not directly affect evolution by natural selection.
II. Favourable characteristics acquired during lifetime – Incorrect; traits acquired during life (like muscles from exercise) are not passed to offspring.
III. Variation within a species – Correct; genetic variation is necessary for natural selection to act on.
Question
Which statement best describes how evolution occurs?
A. Species which produce the most offspring are favoured by natural selection.
B. Mutations in somatic cells are passed on to offspring.
C. Natural selection decreases the frequency of unfavourable characteristics.
D. Changes in species lead towards greater complexity over time.
▶️Answer/Explanation
Answer: C. Natural selection decreases the frequency of unfavourable characteristics.
Explanation:
Evolution happens through natural selection, where individuals with favourable traits survive and reproduce more, causing those traits to become more common. Mutations in reproductive cells (not somatic cells) create variation. Evolution doesn’t always mean increasing complexity—sometimes simpler forms are favoured.
Evaluation of Each Option:
A. Incorrect – Producing many offspring alone doesn’t guarantee evolutionary success; it’s the survival and reproduction of those with favourable traits that matters.
B. Incorrect – Mutations in somatic cells (body cells) are not inherited; only mutations in reproductive cells are passed to offspring.
C. Correct – Natural selection reduces the frequency of unfavourable traits by making individuals with those traits less likely to survive and reproduce.
D. Incorrect – Evolution does not always lead to greater complexity; it depends on what traits improve survival.
Question
What could be used as evidence for evolution?
I. Selective breeding of domesticated animals
II. The fossil record
III. Homologous structures
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
Answer: D. I, II and III
Explanation:
Evidence for evolution includes observable data that show species have changed over time and share common ancestors. This includes fossils, similarities in body structures, and examples of how traits can change under selection.
Evaluation of Each Statement:
I. Selective breeding of domesticated animals – Correct; artificial selection shows how species can change over generations.
II. The fossil record – Correct; fossils provide direct evidence of how species have changed through time.
III. Homologous structures – Correct; shared body structures from a common ancestor show evolutionary relationships.
Question
Which is an example of evolution by selective breeding?
A. Selection of prey animals that can run faster than their predators
B. The variation in the size of different breeds of dogs
C. The tendency, during breeding, for birds to produce more offspring than will survive
D. Some female spiders only breeding with males which make the right signals
▶️Answer/Explanation
Answer: B. The variation in the size of different breeds of dogs
Explanation:
Selective breeding (artificial selection) is when humans choose which animals or plants reproduce based on desired traits, causing those traits to become more common over generations.
Evaluation of Each Option:
A. Incorrect – This describes natural selection, not selective breeding by humans.
B. Correct – Different dog breeds with varying sizes result from humans selectively breeding dogs for specific traits.
C. Incorrect – Producing more offspring than survive is natural reproductive behavior, not selective breeding.
D. Incorrect – Female spiders choosing mates is sexual selection (natural), not human-driven selective breeding.
Question
What are the evolutionary origins and functions of homologous structures?
▶️Answer/Explanation
Answer: B
Explanation:
Option A:
Evolutionary origin: Common or different origin
Function: Same function
Incorrect – This is too vague. Homologous structures specifically arise from a common origin, not just “common or different.” Also, the function can differ.
Option B:
Evolutionary origin: Common origin
Function: Same or different function
Correct – This perfectly describes homologous structures. They evolve from a shared ancestor and may have similar or different functions, depending on the environment and adaptations.
Option C:
Evolutionary origin: Different origin
Function: Same function
Incorrect – This actually describes analogous structures, not homologous. Analogous structures have different origins but perform similar functions (like a bat wing and insect wing).
Option D:
Evolutionary origin: Different origin
Function: Same or different function
Incorrect – Again, this describes analogous structures, which are not based on common ancestry.