IB Biology: Heredity

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Questions and Answers

Explain how the semi-conservative nature of DNA replication ensures genetic continuity.

Each new DNA molecule contains one original strand and one newly synthesized strand, ensuring accurate inheritance of genetic information.

Describe the role of DNA ligase in the process of DNA replication.

DNA ligase joins Okazaki fragments on the lagging strand by catalyzing the formation of phosphodiester bonds.

Outline the key differences between mitosis and meiosis in terms of chromosome number changes.

Mitosis maintains the chromosome number, producing two diploid cells. Meiosis halves the chromosome number, producing four haploid cells.

Explain the significance of crossing over during meiosis.

Crossing over creates new combinations of alleles on chromosomes, increasing genetic variation in offspring. Signup and view all the answers

Describe how non-disjunction during meiosis can lead to genetic disorders.

Non-disjunction results in daughter cells with an abnormal number of chromosomes, leading to conditions like Down syndrome. Signup and view all the answers

Explain how a test cross can be used to determine if an organism with a dominant phenotype is homozygous or heterozygous.

Cross the individual with a homozygous recessive. If any offspring show the recessive phenotype, the individual is heterozygous. Signup and view all the answers

Explain how the SRY gene on the Y chromosome determines sex in humans.

The SRY gene triggers the development of testes, leading to the production of testosterone and the development of male characteristics. Signup and view all the answers

Describe how linked genes affect the expected phenotypic ratios in a dihybrid cross.

Linked genes, located on the same chromosome, tend to be inherited together, distorting the expected 9:3:3:1 ratio. Signup and view all the answers

What is the role of restriction enzymes in biotechnology?

Restriction enzymes cut DNA molecules at specific recognition sites, enabling DNA fragments to be inserted into vectors. Signup and view all the answers

Explain how gel electrophoresis is used to separate DNA fragments.

Gel electrophoresis separates DNA fragments based on size, with smaller fragments migrating faster through the gel matrix. Signup and view all the answers

How does the polymerase chain reaction (PCR) amplify a specific DNA sequence?

PCR uses repeated cycles of heating and cooling to denature DNA, anneal primers, and extend the DNA sequence using a DNA polymerase. Signup and view all the answers

Describe one application of genetically modified (GM) crops in agriculture.

GM crops can be engineered to be resistant to herbicides, reducing the need for manual weeding and increasing crop yields. Signup and view all the answers

Outline the process of somatic cell nuclear transfer (SCNT) in cloning.

The nucleus of a somatic cell is transferred into an enucleated egg cell, which is then stimulated to develop into an embryo. Signup and view all the answers

Explain how DNA sequencing provides insights into evolutionary relationships between species.

By comparing DNA sequences, scientists can identify similarities and differences, which reflect the degree of relatedness and evolutionary divergence. Signup and view all the answers

Describe how epigenetic modifications can influence gene expression without altering the DNA sequence.

Epigenetic modifications, such as DNA methylation and histone acetylation, can change chromatin structure, affecting gene transcription. Signup and view all the answers

How does the process of alternative splicing increase protein diversity from a single gene?

Alternative splicing allows different combinations of exons to be included in the final mRNA transcript, producing different protein isoforms. Signup and view all the answers

Explain the role of telomeres in maintaining chromosome integrity and their relevance to cell aging.

Telomeres protect the ends of chromosomes from degradation and fusion. They shorten with each cell division, eventually triggering cell senescence. Signup and view all the answers

Describe how gene therapy can be used to treat genetic disorders.

Gene therapy involves introducing a functional gene into a patient's cells to compensate for a defective gene, correcting the genetic defect. Signup and view all the answers

How can CRISPR-Cas9 technology be used to edit genes in living organisms?

CRISPR-Cas9 uses a guide RNA to target a specific DNA sequence, where the Cas9 enzyme creates a double-strand break, allowing for gene disruption or insertion. Signup and view all the answers

Explain how bioinformatics contributes to our understanding of genomics and proteomics.

Bioinformatics uses computational tools to analyze large biological datasets, such as DNA and protein sequences, to identify genes, predict protein structures, and understand biological processes. Signup and view all the answers

Flashcards

DNA Replication

The process by which a DNA molecule is copied to produce two identical DNA molecules.

Cell Division

The process by which a cell divides to produce two daughter cells.

Inheritance

The process by which traits are passed from parents to offspring.

Biotechnology

The manipulation of organisms or their components to make useful products.

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Study Notes

BioNinja provides resources for the IB Biology course.
Resources include syllabus outlines, command terms, reporting skills, and practical work guidance.
Topics covered: biomolecules, cells, metabolism, genetics, heredity, equilibrium, body systems, plant systems, biodiversity, nutrition, ecology, and human impacts.
Explores themes, including unity and diversity, form and function, interdependencies, and continuity/change.
Offers review materials, including PowerPoints, topic notes, summaries, and worksheets.
Includes resources for both Standard Level and Higher Level content.
Heredity is covered under: replication, cell division, inheritance, gene linkage and biotechnology.

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