Y10 biology exam guide

flashcards for exams

What is DNA?

deoxyribonucleic acid - includes genetic information of a cell/living organism containing the genetic code. Unique to individuals.

Where is DNA located?

Nucleus of eukaryotic cells (animal and plant cells).

What is the function of DNA?

Codes for the production of proteins.

What is the structure of DNA?

Double helix, 2 strands wound around each other, made up of repeating nucleotides (sugar, base, phosphate group).

What are the complementary base pairings in DNA?

A-T, C-G

What is DNA replication?

Process of copying the genetic code to make new cells.

Which enzyme unwinds DNA during replication?

Helicase.

What is the role of SSB proteins in DNA replication?

Keeps the DNA strands open during replication.

Which enzyme creates a primer to start DNA replication?

Primase.

Which enzyme adds nucleotides to the DNA strands during replication?

DNA Polymerase.

Which enzyme removes primers during DNA replication?

Exonuclease.

Which enzyme seals up DNA fragments into a continuous strand?

Ligase.

What is the semi-conservative nature of DNA replication?

The new DNA contains half original strand and half new strand.

What are point mutations?

Mutation in one base pair.

What are frameshift mutations?

Insertion or deletion of one or more bases that causes the protein to be longer or shorter than it should be.

What is the structure of mRNA?

Single-stranded, contains ribose, and uracil.

What is the function of mRNA?

Stores information about how to make a protein and can leave the nucleus.

What is transcription?

DNA is converted to mRNA.

What is protein synthesis?

Proteins are produced from amino acids in two main steps: transcription and translation.

What happens during translation?

mRNA leaves nucleus, attaches to a ribosome, and is read to produce a polypeptide chain.

What is a codon chart used for?

Used to determine the amino acid that each codon codes for.

What is mitosis?

Somatic cells divide via mitosis.

What are the phases of mitosis?

Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis (PMAT).

What are the products of mitosis?

2 diploid (2n) daughter cells genetically identical to the parent cell.

What is the function of mitosis?

Growth and repair.

What is meiosis?

Gametes (sex cells) divide via meiosis.

What are the products of meiosis?

4 haploid (n) daughter cells genetically different to the parent cell.

What is the function of meiosis?

Sexual reproduction.

What is a gene?

Sections of DNA that code for traits.

What is an allele?

Different forms of the same gene.

What is a chromosome?

Long strands of DNA wrapped around a protein (histone).

What is a genotype?

Exact pairing of alleles (e.g., RR, Rr, rr).

What is a phenotype?

Expression of the trait (what you actually see).

What is a Punnett square?

Used to predict the possible genotypes of the offspring of two organisms.

What are the characteristics of autosomal dominant inheritance?

Each affected person has an affected parent and occurs in every generation.

What are the characteristics of autosomal recessive inheritance?

Both parents of an affected person are carriers and is not seen in every generation.

How is a dominant allele represented?

Represented with uppercase letters (B, E, R, T).

How is a Recessive Allele represented?

Represented with lowercase letters (b, e, r, t).

What is Genetic Variation:

Differences in DNA among individuals.

What is Phenotype Variation:

Differences in expressed traits among individuals.

What are the Benefits of Biodiversity:

A wide range of species is beneficial to humans, and a wide range of genetic variants within a species is beneficial to that species.

What are the Causes of Genetic Variation:

1. Independent Assortment 2. Crossing Over/Recombination 3. Random Fertilization 4. Mutations of DNA

What is adaptation?

special features that help an organism survive in their environment.

What are the types of adaptaions?

1. Structural: changes to an organism's physical structure (e.g, fur) 2. Behavioral: modifications to an organism's actions -> things the animal actually does (e.g., penguins huddling) 3. Physiological: adaptations to an organism's internal functioning (can't see happening - inside body e.g., snake producing venom)

What is evolution?

evolution is when species change to suit their environment over time, and sometimes changing into another species

What are types of evolution?

1. Divergent Evolution: evolution of 2 or more different species from a common single ancestral species -> possess homologous features (features w a common origin but a different function) 2. Convergent Evolution: unrelated species that have adapted to particular environments in similar ways -> possess analogous features (features w a different origin w a similar function) 3. Co-evolution: evolution in which one organism causes another to change since they live in close association -> exert selective pressures on each other

What are homologous features?

features with a common origin but a different function -> provide evidence for divergent evolution.

What are Analogous Features:

features with different origin but a similar function. Provide evidence for convergent evolution.

What are extinctions?

The state or process of a species, family, or larger group being or becoming extinct.

What is the evidence of evolution?

1. Palaeontology (fossils) 2. Biogeography 3. Comparative anatomy 4. Developmental biology 5. Molecular evidence

What are Fossils?

The preserved remains or traces of ancient organisms.

What is Relative Dating:

Comparing rock strata (layers) to determine relative age.

What is Absolute Dating:

Use chemical make-up of the fossil to determine the exact age.

What are Cladogram and Phylogenetic Tree:

Branching diagrams that illustrate evolutionary relationships between different groups of organisms.

What are Character Table:

Table that shows the presence or absence of certain traits in different organisms.

What is Interpretation:

Understanding the relationships between organisms based on shared characteristics.

What is Pedigree Tree Function:

Used to show how genetic disorders are inherited in a family.

What is Interpretation:

Determining if a trait is dominant or recessive.

What is Evolution:

a change in heritable traits within a population over time.

What are Allels:

variations of a gene.

What are Genes:

sections of DNA that code for traits.

What is a Chromosome:

long strands of DNA wrapped around a protein.

What is a Genotype:

the genetic makeup of an organism.

What is a Phenotype:

the physical expression of the genotype.

What is Convergent Evolution:

evolution of unrelated species to have similar traits.

What is Speciation:

the evolution of a new species.

What is the Bottleneck Effect:

a catastrophic event reduces population size, altering allele frequencies.

What is the Founder's Effect:

a small group colonizes a new habitat, leading to different allele frequencies.

What is Divergent Evolution:

evolution of a common ancestor into different species.

What is Gene Flow:

transfer of genetic material from one population to another.

What is natural selection?

the process by which organisms with favorable traits survive and reproduce.

What is Mutation:

a change in the DNA sequence

What is is Insertion:

+ of a base.

What is Deletion:

- of a base.

What is Substitution:

replacement of one base with another.

What is DNA Polymerase:

enzyme that adds nucleotides during DNA replication.

What is Helicase:

enzyme that unwinds DNA.

What is Ligase:

enzyme that seals DNA fragments.

What are Fossils:

preserved remains of ancient organisms.

What is the Fossil record?

the history of life documented by fossils.