VCAA Biology How are species related over time?

This is incorrect because specimens should not be exposed to decomposers (II). Decomposers break down organic matter, which prevents fossilisation.

This is incorrect because both exposure to decomposers (II) and disturbance (V) would destroy the specimen before it has a chance to fossilise.

This is incorrect because exposure to decomposers (II) and physical disturbance (V) actively destroy remains, making fossilisation impossible.

This sequence differs from the human sequence at two positions (Lys instead of Ile, and Met instead of Glu), making it less similar than Option B.

This sequence differs from the human sequence at three positions (Asp, Leu, and Met), making it less similar than Option B.

This sequence differs from the human sequence at two positions (Val instead of Glu, and Asn instead of Ile), making it less similar than Option B.

Bipedalism and an upright stance actually decreased tree-climbing efficiency, as hominins lost the grasping feet and specialized limb proportions that make other apes excellent climbers.

While bipedalism freed the hands to carry food, it did not increase upper body strength. In fact, hominins generally have less upper body strength compared to their quadrupedal ape relatives.

Bipedal hominins are generally slower runners than quadrupedal animals. Bipedalism evolved for endurance and energy efficiency over long distances, not for sprinting to outrun predators.

Genetic drift involves random changes in allele frequencies, which actually tends to increase genetic differences between isolated populations over time.

Speciation is the process by which populations evolve to become distinct species, which requires an increase in genetic differences, not a reduction.

Mutations introduce new, random alleles into a population. Because they occur independently in different populations, they tend to increase genetic divergence rather than reduce it.

This scenario describes a population bottleneck or the path to extinction, rather than the divergence process required to form a new species.

While selection pressures drive microevolution by changing allele frequencies, speciation specifically requires reproductive isolation to separate a lineage into distinct species.

Genetic drift is a constant evolutionary force in finite populations, and its cessation is not a mechanism for speciation.

While mitochondrial DNA does code for enzymes involved in cellular respiration, this functional characteristic does not help scientists trace historical migration pathways.

Mitochondrial DNA is not identical within populations; in fact, the gradual accumulation of mutations over time creates distinct genetic markers (haplogroups) that scientists use to track migrations.

Mitochondrial DNA actually has a higher mutation rate than nuclear DNA due to its lack of protective histones and exposure to reactive oxygen species, so it is not more structurally stable.

Incorrect. Protists are eukaryotes that evolved much later, and 3.5 million years ago is far too recent for the earliest signs of life.

Incorrect. While 3.5 billion years ago is the correct timeframe for the earliest life, protists are eukaryotes and did not appear until roughly 1.5 to 2 billion years ago.

Incorrect. Although prokaryotes are the earliest known life forms, they first appeared 3.5 billion years ago, not 3.5 million.

Comparative embryology focuses on the development of embryos across different species, which provides evidence for evolution but is not the study of evolutionary history itself.

Comparative anatomy is the study of structural similarities and differences between species, which is used to build phylogenetic trees but is not the definition of phylogeny.

The study of fossils and the fossil record is called paleontology, though fossil data is often used to determine phylogeny.

Humans do not have extra wrist bones compared to other primates; our wrist structure is actually adapted for a balance of flexibility and strength.

Long, curved finger bones are characteristic of arboreal primates (like chimpanzees) for climbing and hanging, whereas human fingers are shorter and straighter.

Humans actually have a relatively short and broad palm compared to the long, narrow palms of many other primates that are adapted for climbing.

Low levels of inbreeding typically indicate higher genetic diversity, which provides the variation necessary for a population to adapt to a changing environment.

Low levels of inbreeding and a stable environment are ideal conditions for population survival, making the population highly resilient rather than vulnerable.

Although low genetic diversity is a risk factor, a stable environment means the population is not currently facing new selective pressures that would require adaptation, making it less vulnerable than if the environment were changing.

A small gene pool typically leads to genetic drift or inbreeding depression, which reduces genetic diversity rather than driving the formation of a new species.

This describes gene flow, which actually prevents speciation by keeping the genetic makeup of the two populations similar.

If individuals can interbreed freely, gene flow is still occurring, which prevents the populations from diverging enough to become separate species.

Amino acid sequences accumulate mutations over time, making them highly useful for comparing genetic divergence and determining evolutionary relationships among different mammals.

Protein sequences provide valuable molecular data for constructing phylogenetic trees, as comparing their similarities and differences helps identify how closely related different species are.

Variations in bone structure (homologous structures) provide important morphological evidence that helps biologists distinguish and group different mammalian lineages.