How many SCSA Human Biology questions cover Hominid evolutionary trends?

AusGrader has 70 SCSA Human Biology questions on Hominid evolutionary trends, all with instant AI grading and detailed marking feedback.

SCSA Human Biology Hominid evolutionary trends

5 sample questions with marking guides and sample answers

Q22

2025

SCSA

1 mark

Q22

1 mark

Scientists suggest that some hominin adaptations, including an upright stance and bipedal locomotion, were associated with a drier habitat and expanding grasslands.

Which of the following best explains the advantage of an upright stance and bipedal locomotion in the African savannah? It

allowed hominins to climb trees more effectively to escape predators in open grasslands.

increased the ability of hominins to spot prey and forage for food over long distances.

increased upper body strength so hominins could gather and carry larger quantities of food.

allowed hominins to develop faster running speeds, allowing them to outrun predators.

Q11

2025

SCSA

1 mark

Q11

1 mark

The human hand can be distinguished from most other primates by its

extra bones in the wrist that increase strength but reduce flexibility.

opposable thumb that improves dexterity and allows for a precision grip.

long, curved finger bones that enable a power grip to exert force.

long and narrow palm that is designed for efficient grasping and climbing.

Q42

2020

SCSA

20 marks

Q42

Species of the genus Homo do not possess the powerful jaw muscles commonly found in the genera Australopithecus and Paranthropus. According to the fossil record, this decrease in the size of jaw muscles coincided with changes in brain size. Scientists have discovered that both the reduction in the size of the jaw muscles and the change in brain size occurred due to mutations.

Q42a

15 marks

Describe the various types of mutations, identify the causes and describe how they can occur.

A mutation is a change in a gene or a chromosome, leading to new characteristics in an organism or their offspring.

Mutations can be gene mutations or chromosomal mutations. Gene mutations are changes in a single gene which occur during DNA replication, while chromosomal mutations affect all or part of a chromosome. Mutations can also be somatic or germline. Somatic mutations occur in the body cells, meaning reproductive cells are not affected and therefore the mutation is not passed on to offspring. Germline mutations occur in the reproductive cells or gametes, and therefore can be passed on to offspring.

Mutations can be caused by mutagenic agents, which are substances that are known to increase the rate at which mutations occur, such as ionising radiation (e.g. X-rays), mustard gas, formaldehyde, and some antibiotics. Mutations can also be caused by errors in DNA replication, resulting in deletion where part of a chromosome is lost, duplication where a section of chromosome is repeated or occurs twice, etc. Finally, mutations can be caused by errors in cell division, leading to inversion where a broken part of a chromosome joins back but in the wrong way, translocation where part of a chromosome breaks off and re-joins to the wrong chromosome, etc.

Marking Criteria

Define

Descriptor	Marks
Defines a mutation as a change in a gene or a chromosome (leading to new characteristics in an organism or their offspring)	1

Types of mutations

Descriptor	Marks
1 mark for each valid point (up to 3 marks): States mutations can be gene mutations or chromosomal mutations Describes gene mutations as changes in a single gene (which occurs during DNA replication) Describes chromosomal mutations as affecting all or part of a chromosome	3
1 mark for each valid point (up to 3 marks): States mutations can be somatic or germline Describes somatic mutations as occurring in the body cells (reproductive cells are not affected) therefore the mutation is not passed on to offspring Describes germline mutations as occurring in the reproductive cells/gametes therefore can be passed on to offspring	3

Causes - Mutagens

Descriptor	Marks
States mutations are caused by mutagens/mutagenic agents	1
Defines mutagens as substances that are known to increase the rate at which mutations occur (e.g. ionising radiation, mustard gas, formaldehyde, some antibiotics)	1

Causes - DNA replication

Descriptor	Marks
States mutations are caused by errors in DNA replication	1
1 mark for each valid point (up to 2 marks): Deletion: part of a chromosome is lost; Duplication: section of chromosome is repeated/occurs twice; Insertions: DNA can be duplicated/extra DNA added; Frameshifts: incomplete DNA code/unreadable DNA code	2

Causes - Cell division

Descriptor	Marks
States mutations are caused by errors in cell division/meiosis	1
1 mark for each valid point (up to 2 marks): Inversion: broken part of chromosome joins back but in the wrong way; Translocation: part of chromosome breaks off and re-joins to the wrong chromosome; Non-disjunction: during meiosis, a chromosome pair does not separate so one daughter cell has an extra chromosome and one daughter cell has one less (aneuploidy)	2

Q42b

5 marks

Explain how the example of the evolution of the unique hominin jaw illustrates the importance of mutations to evolution.

Mutations introduce new alleles into a population. Hominin jaw mutations must have been an advantage to survival, as the organisms are better suited to bipedal locomotion. These favourable alleles are passed onto offspring, meaning the mutation is maintained in future generations.

Marking Criteria

Descriptor	Marks
Award 1 mark for each of the following points, up to a maximum of 5 marks: States that mutations introduce new alleles into a population Explains that hominin jaw mutations must have been favourable or an advantage to survival Explains that organisms are better suited to bipedal locomotion, balance of the head in bipedal locomotion, stereoscopic vision, or that it helped enable increases in cranial capacity States that favourable alleles are passed onto offspring States that the mutation is maintained in the population or future generations	5

Descriptor

Marks

Award 1 mark for each of the following points, up to a maximum of 5 marks:

States that mutations introduce new alleles into a population
Explains that hominin jaw mutations must have been favourable or an advantage to survival
Explains that organisms are better suited to bipedal locomotion, balance of the head in bipedal locomotion, stereoscopic vision, or that it helped enable increases in cranial capacity
States that favourable alleles are passed onto offspring
States that the mutation is maintained in the population or future generations

Q41

2021

SCSA

20 marks

Q41

It is estimated that millions of hominins pre-dating the modern Homo sapiens have populated the Earth and yet only 6000 individuals are represented in the hominin fossil record.

Q41a

10 marks

Explain why there are so few fossils in the fossil record.

Generally only hard or solid parts, such as bones and teeth, are fossilised. Organisms need to ‘die’ in an area suitable to fossilisation, and the sediments or soils need to be of the right conditions. Organisms need to be protected from decay from microorganisms, and the remains need to be undisturbed by scavengers. The remains need to be quickly covered by sediments for rapid burial, and the sediments need to be undisturbed by geological processes. Many fossils are buried too deep to be found. Many fossils are destroyed by geological processes or human activity, and many fossils are not recognised as being so. Finally, many fossils once exposed are eroded or weathered.

Marking Criteria

Descriptor	Marks
1 mark for each correct point (any 10 of): Generally only hard/solid parts e.g. bones/teeth are fossilised; Organisms need to ‘die’ in area suitable to fossilisation; The sediments/soils needs to be of the right conditions/alkaline/low oxygen levels; Organisms need to be protected from decay from microorganisms; The body/remains need to be undisturbed by scavengers; The body/remains need to be quickly covered by sediments/rapid burial; The soil/sediments need to be undisturbed by geological processes; Many fossils are buried too deep to be found/not exposed to the surface; Many fossils are destroyed by geological processes/human activity; Many fossils are not recognised as being so/people don’t recognise them; Many fossils once exposed are eroded/weathered	10

Descriptor

Marks

1 mark for each correct point (any 10 of): Generally only hard/solid parts e.g. bones/teeth are fossilised; Organisms need to ‘die’ in area suitable to fossilisation; The sediments/soils needs to be of the right conditions/alkaline/low oxygen levels; Organisms need to be protected from decay from microorganisms; The body/remains need to be undisturbed by scavengers; The body/remains need to be quickly covered by sediments/rapid burial; The soil/sediments need to be undisturbed by geological processes; Many fossils are buried too deep to be found/not exposed to the surface; Many fossils are destroyed by geological processes/human activity; Many fossils are not recognised as being so/people don’t recognise them; Many fossils once exposed are eroded/weathered

Q41b

10 marks

Explain, using examples, how the comparative studies of anatomy can be used for the construction of phylogenetic trees.

Any 2 of comparative embryology, homologous structures, or vestigial organs

For comparative embryology:
We compare anatomical structure during embryo development. Organisms share similar anatomical structures during early development, which indicates shared common ancestry. The more similar the structures are for longer in the embryonic stage, the more closely placed together they are on phylogenetic trees. An example is gill slits and a tail found in vertebrate embryos.

For homologous structures:
We compare anatomical structure from different species. Structures show a high degree of structural similarity but perform different functions, which indicates shared common ancestry. The more similar the structures are, the more closely placed together they are on phylogenetic trees. An example is the bone structure in the vertebrate limbs.

For vestigial organs:
These are homologous structures that have a benefit in some species, but are present but not functional in other species. This indicates shared common ancestry. More shared features mean they are more closely placed together on phylogenetic trees. An example is wisdom teeth in humans.

Marking Criteria

Example 1

Descriptor	Marks
1 mark for each correct point for one chosen example: Comparative embryology (Compares anatomical structure during embryo development/stages of embryo development from different species; States that organisms share similar anatomical structures during early development; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are for longer in the embryonic stage = more closely placed together on phylogenetic trees; Provides an example); OR Homologous structures (Compares anatomical structure from different species; States that structures show a high degree of structural similarity but perform different functions; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are = more closely placed together on phylogenetic trees; Provides an example); OR Vestigial organs (Describes homologous structures that have a benefit/normal function in some species; States that they are present but not functional in other species; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the structure; Explains that more shared features = more closely placed together on phylogenetic trees; Provides an example).	5

Descriptor

Marks

1 mark for each correct point for one chosen example: Comparative embryology (Compares anatomical structure during embryo development/stages of embryo development from different species; States that organisms share similar anatomical structures during early development; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are for longer in the embryonic stage = more closely placed together on phylogenetic trees; Provides an example); OR Homologous structures (Compares anatomical structure from different species; States that structures show a high degree of structural similarity but perform different functions; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are = more closely placed together on phylogenetic trees; Provides an example); OR Vestigial organs (Describes homologous structures that have a benefit/normal function in some species; States that they are present but not functional in other species; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the structure; Explains that more shared features = more closely placed together on phylogenetic trees; Provides an example).

Example 2

Descriptor	Marks
1 mark for each correct point for a second chosen example: Comparative embryology (Compares anatomical structure during embryo development/stages of embryo development from different species; States that organisms share similar anatomical structures during early development; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are for longer in the embryonic stage = more closely placed together on phylogenetic trees; Provides an example); OR Homologous structures (Compares anatomical structure from different species; States that structures show a high degree of structural similarity but perform different functions; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are = more closely placed together on phylogenetic trees; Provides an example); OR Vestigial organs (Describes homologous structures that have a benefit/normal function in some species; States that they are present but not functional in other species; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the structure; Explains that more shared features = more closely placed together on phylogenetic trees; Provides an example).	5

Descriptor

Marks

1 mark for each correct point for a second chosen example: Comparative embryology (Compares anatomical structure during embryo development/stages of embryo development from different species; States that organisms share similar anatomical structures during early development; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are for longer in the embryonic stage = more closely placed together on phylogenetic trees; Provides an example); OR Homologous structures (Compares anatomical structure from different species; States that structures show a high degree of structural similarity but perform different functions; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the basic structure; Explains that the more similar the structures are = more closely placed together on phylogenetic trees; Provides an example); OR Vestigial organs (Describes homologous structures that have a benefit/normal function in some species; States that they are present but not functional in other species; Explains that this indicates shared common ancestry/at one point they all shared an ancestor who had the structure; Explains that more shared features = more closely placed together on phylogenetic trees; Provides an example).

Q39

2024

SCSA

20 marks

Q39

Researchers in Ethiopia found a relatively complete hominin skeleton. Looking at the skeleton it was not clear which form of locomotion the hominin had used. The specimen showed features that could be linked with both bipedalism and brachiation.

Q39a

10 marks

Identify six anatomical features of the skeleton that could have been present in the shoulders, arms, and hands to support brachiation as a means of locomotion, and explain how the shoulders, arms and hands allow for brachiation.

Features of brachiation include:

Shoulders with a reduced clavicle, high shoulder blades, and a backwards facing socket of the scapula.
Longer arms and a flexible elbow joint.
The hands have long, curved fingers, short thumbs, and a robust but flexible wrist joint.

These features are adapted for swinging in trees. The hands are adapted to grasp branches. These adaptations provide strength to support the weight of the hominin in trees and create an energy efficient pattern of movement.

Marking Criteria

Descriptor	Marks
1 mark for each correct point (any 6 of, with at least one from each category): Shoulders: short/reduced clavicle, high shoulder blades, mobile shoulder joint/backwards facing socket of scapula Arms: longer arms/smaller arm to leg ratio/long, robust humerus/long, slender radius and ulna, flexible elbow joint Hands: long, curved fingers, short thumbs, robust but flexible wrist joint	6
Explains that these features are adapted for swinging in trees, circular arm movements, or flexibility of arms to rotate	1
Explains that hands are adapted to grasp branches or hang from branches	1
States that these adaptations provide strength to support the weight of the hominin in trees	1
Concludes that this creates an energy efficient pattern of movement	1

Q39b

4 marks

Identify two anatomical features of the skeleton that could have been present in the pelvis to support bipedalism as a means of locomotion, and outline how these features would allow for bipedalism.

The pelvis: short, broad, and bowl-shaped pelvis

These features ensure support of body organs and help propel the body forward during locomotion.

Marking Criteria

Descriptor	Marks
1 mark for each correct point (any 2 of): wide pelvis/short and broad pelvis bowl-shaped pelvis; forward facing acetabulum robust sacroiliac joint/sacrum to ilium joint reduced iliac crest	2
1 mark for each correct point (any 2 of): ensures weight-bearing/support of body organs helps propel the body forward during locomotion creates energy efficient pattern of movement provides a large area for muscle attachment creates balance/stability creates the striding gait motion	2

Q39c

6 marks

Researchers were unable to provide an actual date for the fossil skeleton. They were however, able to use stratigraphy to date the fossil.

Name and describe two ways in which stratigraphy is employed to date a fossil.

The principle of superposition states that the youngest rocks are at the top, while the oldest are underneath, meaning fossils higher in the layers are younger.

The correlation of rock strata involves rock strata from one location being matched with another location, so fossils in matching rock strata are the same age.

Marking Criteria

Descriptor	Marks
Identifies the principle of superposition	1
Explains that the youngest rocks are at the top, while the oldest are underneath	1
States that fossils higher in the layers are younger	1
Identifies the correlation of rock strata	1
Explains that rock strata from one location are matched with another location	1
States that fossils in matching rock strata are the same age, or mentions matching index fossils to determine age	1

SCSA Human Biology Hominid evolutionary trends

Define

Types of mutations

Causes - Mutagens

Causes - DNA replication

Causes - Cell division

Example 1

Example 2

Frequently Asked Questions

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