International Baccalaureate Diploma (IB) Group 4: Sciences (Biology) Flashcards

24 sample cards from the Group 4: Sciences (Biology) deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. Distinguish mitosis from meiosis.

   Mitosis produces two genetically identical diploid cells for growth and repair; meiosis produces four genetically varied haploid gametes through two divisions, halving the chromosome number.

2. Name the four stages of mitosis in order and what happens in each.

   Prophase: chromosomes condense, spindle forms. Metaphase: chromosomes align at the equator. Anaphase: sister chromatids separate to opposite poles. Telophase: nuclear membranes reform around two sets of chromosomes.

3. How does meiosis generate genetic variation?

   Through crossing over (exchange of alleles between homologous chromosomes in prophase I) and independent assortment (random orientation of homologous pairs at metaphase I).

4. Contrast asexual and sexual reproduction.

   Asexual involves one parent and produces genetically identical clones (no gametes); sexual involves two parents and fusion of gametes, producing genetically varied offspring.

5. Define genotype, phenotype, allele, and homozygous.

   Genotype: an organism's genetic makeup. Phenotype: its observable characteristics. Allele: an alternative version of a gene. Homozygous: having two identical alleles for a gene.

6. In a monohybrid cross between two heterozygotes (Tt x Tt), what is the expected phenotype ratio?

   3:1 dominant to recessive (genotype ratio 1 TT : 2 Tt : 1 tt).

7. What is codominance, and give an example?

   Both alleles are fully expressed in the heterozygote, neither masking the other; e.g. the AB blood group, where both A and B antigens are present.

8. How is sex determined in humans, and why are males more likely to show X-linked recessive conditions?

   Females are XX, males are XY. Males have only one X chromosome, so a single recessive allele on it is expressed (no second X to mask it).

9. What is a gene mutation and how can it affect a protein?

   A change in the DNA base sequence; it can alter the amino acid sequence of a protein, potentially changing its structure and function (e.g. sickle-cell anaemia).

10. State Darwin's theory of evolution by natural selection in four steps.

    Variation exists in populations; more offspring are produced than can survive (overproduction/competition); individuals with advantageous traits survive and reproduce more (survival of the fittest); these traits are inherited, so the population changes over generations.

11. List four types of evidence for evolution.

    The fossil record, comparative anatomy (homologous structures), molecular/biochemical similarities (DNA and proteins), and direct observation (e.g. antibiotic resistance, selective breeding).

12. Distinguish homologous from analogous structures.

    Homologous structures share a common evolutionary origin but may differ in function (e.g. pentadactyl limbs), showing divergent evolution; analogous structures share function but not origin (e.g. bird and insect wings), showing convergent evolution.

13. What is biodiversity and why is it important?

    The variety of life at genetic, species and ecosystem levels; it increases ecosystem stability and resilience, provides resources and services, and offers a genetic reservoir for future adaptation.

14. How does antibiotic resistance in bacteria illustrate natural selection?

    Random mutation gives some bacteria resistance; when antibiotics are applied, susceptible bacteria die while resistant ones survive and reproduce, so the resistant allele spreads through the population.

15. Define independent, dependent, and controlled variables.

    Independent: the variable deliberately changed by the experimenter. Dependent: the variable measured as the outcome. Controlled: variables kept constant to ensure a fair test.

16. What is the difference between accuracy and precision?

    Accuracy is how close a measurement is to the true value; precision is how close repeated measurements are to each other (reproducibility), regardless of correctness.

17. Distinguish a random error from a systematic error.

    Random errors cause unpredictable scatter around the true value and are reduced by repeating measurements; systematic errors shift all readings consistently in one direction (e.g. miscalibration) and are not reduced by repetition.

18. What is a null hypothesis?

    A statement that there is no significant difference or relationship between the variables; statistical tests aim to reject or fail to reject it.

19. Why are repeats and a large sample size important in an experiment?

    They reduce the effect of random error and anomalies, allow calculation of a reliable mean, and increase confidence that results are representative and statistically significant.

20. What does a standard deviation tell you about a data set?

    It measures the spread of data around the mean; a small standard deviation indicates data clustered close to the mean (consistent), a large one indicates wide variability.

21. What is a controlled (negative) control and why is it used?

    A treatment with the independent variable absent or at baseline; it shows what happens without the tested factor, providing a comparison to confirm the variable caused any observed effect.

22. What are the key stages of the scientific method in an investigation?

    Make an observation, ask a question, form a testable hypothesis, design and conduct an experiment, collect and analyse data, draw a conclusion, and evaluate/communicate results.

23. What is the purpose of the IB Internal Assessment (individual scientific investigation)?

    To let a student plan, carry out and evaluate an independent inquiry into a research question of personal interest, demonstrating experimental and analytical skills.

24. What is the aim of the IB Collaborative Sciences Project?

    An interdisciplinary, collaborative activity in which students work together to address a real-world problem using scientific understanding from multiple disciplines, focusing on the role of science in a global context.

What this deck covers

Group 4: Sciences (Biology) flashcards FAQ