Biology Unit 2 - Exam Revision

Question 1

Distinction between genes, alleles, and a genome

Answer 1

Genes: Basic units of heredity, consisting of DNA sequences that code for proteins, affecting physical and biochemical traits.

Alleles: Different variants of a gene; for example, a gene for flower colour may have a purple allele and a white allele.

Genome: The complete set of genetic instructions for an organism, encompassing all of its genes along with non-coding DNA.

Question 2

Homologous chromosomes and their gene loci

Answer 2

Homologous chromosomes are pairs that contain the same genes at corresponding loci, but may have different alleles (e.g., one is inherited from the mother and the other from the father).

Question 3

Difference between autosomes and sex chromosomes

Answer 3

Autosomes: Non-sex chromosomes that determine traits unrelated to sex (e.g., chromosome pairs 1-22 in humans).

Sex chromosomes: Chromosomes that determine sexual characteristics (e.g., X and Y chromosomes).

Question 4

Variability in size and number of chromosomes in different organisms

Answer 4

E.g, Humans have 46 chromosomes, while fruit flies have 8. The number and structure of chromosomes can vary widely between species, affecting genetic information.

Question 5

Karyotypes and identification of chromosome abnormalities

Answer 5

A karyotype is a comprehensive display of an organism’s chromosomes arranged by size and shape. Karyotypes can be used to identify genetic disorders such as Down syndrome (47, XX or XY +21), characterised by the presence of an extra copy of chromosome 21.

Question 6

Meiosis and its role in producing haploid gametes from diploid cells

Answer 6

Meiosis is a two-staged cell division process (Meiosis I and II) that reduces the chromosome number by half, producing four haploid gametes (sperm or eggs) from one diploid cell.

Question 7

Significance of crossing over and independent assortment in genetic diversity

Answer 7

• Crossing over allows for the exchange of genetic material between homologous chromosomes during prophase I of meiosis, increasing genetic variation.
• Independent assortment occurs in metaphase I, where chromosomes are distributed to daughter cells independently of one another, resulting in a mix of maternal and paternal chromosomes in gametes.

Question 8

Use of symbols to write genotypes

Answer 8

Genotypes are represented using symbols, where uppercase letters signify dominant alleles (e.g., A) and lowercase letters signify recessive alleles (e.g., a).

Question 9

Expression of dominant and recessive phenotypes (including codominance and incomplete dominance)

Answer 9

An organism with at least one dominant allele (e.g., AA or Aa) expresses the dominant phenotype, while organisms with two recessive alleles (aa) express the recessive phenotype.

Codominance occurs when both alleles in a heterozygous individual contribute equally to the phenotype (e.g., AB blood type).

Incomplete dominance results in a blended phenotype (e.g., pink flowers from red (RR) and white (WW) parents).

Question 10

Influence of genetic material, environment, and epigenetic factors on phenotypes

Answer 10

Genetic makeup provides the blueprint for traits, but environmental influences (e.g., sunlight, nutrition) and epigenetic modifications (e.g., DNA methylation) can alter gene expression, leading to variations in phenotypes.

Question 11

Pedigree charts and patterns of inheritance (autosomal and sex-linked)

Answer 11

Pedigree charts illustrate the inheritance of traits across multiple generations, allowing examination of autosomal traits (inherited via non-sex chromosomes) and sex-linked traits (associated with genes on sex chromosomes like colour blindness, which is X-linked).

Question 12

Predicted genetic outcomes for monohybrid crosses

Answer 12

Monohybrid crosses consider one trait (e.g., flower colour) and utilise a Punnett square to predict ratios of expected genotypes (1 homozygous dominant: 2 heterozygous: 1 homozygous recessive) and phenotypes in the offspring.

Question 13

Linked genes vs. independent assortment in inheritance predictions

Answer 13

Genes located close together on the same chromosome are said to be linked, leading to fewer recombinant offspring. In contrast, independently assorting genes generate a variety of combinations.

Question 14

Biological advantages and disadvantages of asexual reproduction

Answer 14

Asexual reproduction (e.g., binary fission in bacteria) enables rapid reproduction and colonisation, resulting in large populations. However, it yields little genetic diversity, making populations vulnerable to diseases and environmental changes.

Question 15

Biological advantages of sexual reproduction, especially in promoting genetic diversity

Answer 15

Sexual reproduction leads to increased genetic variability through the mixing of parental genes, which enhances the adaptability of populations in a changing environment and allows for natural selection to act on more diverse traits.

Question 16

Reproductive cloning technologies and their applications

Answer 16

Cloning techniques (e.g, somatic cell nuclear transfer) raise ethical issues but can be employed to save endangered species or for agricultural benefits. However, cloning can lead to reduced genetic diversity in populations.

Question 17

Importance of genetic diversity within a species or population

Answer 17

Genetic variability within a population fosters resilience to environmental stresses and enables adaptation to changing conditions, reducing the risk of extinction.

Question 18

Structural, physiological, and behavioural adaptations that enhance survival

Answer 18

Structural adaptations: Physical features that enhance survival (e.g., camouflage, specialised teeth).

Physiological adaptations: Internal processes that aid survival (e.g., thermoregulation in mammals).

Behavioural adaptations: Activities or patterns that increase chances of survival (e.g., migration to find food).

Question 19

Survival through interdependencies (e.g., impact of keystone species and top predators)

Answer 19

Keystone species play critical roles in maintaining ecological balance (e.g, sea otters controlling sea urchin populations), while top predators regulate prey populations, ensuring ecosystem stability and biodiversity.

Question 20

Contributions of Aboriginal and Torres Strait Islander knowledge regarding species adaptations and interdependencies

Answer 20

Traditional ecological knowledge from Aboriginal and Torres Strait Islander peoples provides insights into species co-evolution and sustainable practices, helping to conserve biodiversity and ecosystem health.

Question 21

Difference between primary and secondary data

Answer 21

Primary data is direct evidence (e.g., experimental results, field studies), while secondary data involves comprehensive analyses of previously published studies or existing data.

Question 22

Distinguishing opinion, anecdote, and evidence

Answer 22

It is essential to distinguish personal opinions and anecdotal evidence from scientifically validated results when forming conclusions about bioethical issues.

Question 23

Validity and authority of data; identifying possible errors or biases

Answer 23

Assess the credibility of sources by examining methodology, peer-reviewed status, and potential conflicts of interest, while being mindful of biases which could skew results.

Question 24

Organising, analysing, and evaluating secondary data

Answer 24

Effectively compile and dissect secondary data to identify trends, relationships, and discrepancies in scientific literature regarding a bioethical issue.

Question 25

Accurate use of biological concepts and terminology

Answer 25

Precision in scientific language is paramount to avoid misinterpretation; familiarity with terms like genotype, allele frequency, and genetic drift is necessary.

Question 26

Clarity, conciseness, and coherence in communication

Answer 26

Structure arguments and presentations with clear objectives, logical progression, and concise language to maximise impact and understanding.

Question 27

Use of data representations, models, and theories in explaining concepts

Answer 27

Graphical representations (charts, bar graphs, etc.) and models (like Hardy-Weinberg equilibrium) can simplify complex information, making it more accessible.

Question 28

Social, economic, legal, and political factors in bioethical discussions

Answer 28

An encompassing view of bioethical issues must consider the broader societal implications, including how legal frameworks, social justice concerns, and economic pressures influence policies and practices.

Question 29

Referencing and acknowledging sources

Answer 29

Employ consistent citation styles (e.g., APA, MLA) when documenting sources to uphold academic integrity and support arguments with credible evidence.

Question 30

Identifying bioethical issues in genetics, inheritance, or adaptations

Answer 30

Investigate current topics such as genetic modification, cloning ethics, and implications of CRISPR technology, assessing potential benefits and risks.

Question 31

Approaches to bioethics and ethical concepts relevant to the selected issue

Answer 31

Consider various ethical frameworks (e.g., utilitarianism – maximising benefits; deontology – adherence to rules) and principles like autonomy, justice, and beneficence when evaluating the moral dimensions of bioethical dilemmas.