GCSE Biology (CB1–CB6) Flashcards

Cell

Basic unit of life.

Nucleus

Organelle that controls cell activities.

Mitochondria

Organelles that release energy during respiration.

Ribosomes

Cellular structures that make proteins.

Cell membrane

Structure that controls what enters and leaves the cell.

Cytoplasm

Region of the cell where many chemical reactions happen.

Cell wall

Plant cell structure that supports and strengthens plant cells.

Chloroplasts

Organelles that contain chlorophyll to absorb light.

Vacuole

Plant organelle that contains cell sap.

Diffusion

Net movement from high to low concentration.

Osmosis

Water moving through a partially permeable membrane.

Active transport

Movement against a concentration gradient using energy.

Enzyme

A biological catalyst.

Active site

Part of an enzyme where a substrate binds.

Denaturation

Change in enzyme shape.

Factors affecting enzyme activity

Temperature and pH.

Tissue

A group of similar cells.

Organ

Different tissues working together.

Aerobic respiration

Energy release using oxygen.

Anaerobic respiration

Energy release without oxygen.

Mitosis

Division producing identical nuclei for growth and repair.

Daughter cells of mitosis

$2$ genetically identical cells.

Interphase

Cell cycle stage where the cell grows and copies DNA.

Prophase

Mitosis stage where chromosomes condense and spindle forms.

Metaphase

Mitosis stage where chromosomes line up in the middle.

Anaphase

Mitosis stage where sister chromatids separate.

Telophase

Mitosis stage where new nuclei form.

Cytokinesis

Division of the cytoplasm.

Differentiation

Process of cells becoming specialised.

Stem cells

Unspecialised cells that can differentiate.

Embryonic stem cells

Stem cells that can become almost any body cell.

Adult stem cells

Stem cells found in tissues such as bone marrow.

Neuron

A nerve cell that carries electrical impulses.

Reflex

Fast, automatic response.

Receptor

Structure that detects a stimulus.

Effector

A muscle or gland that responds to a stimulus.

CNS (Central Nervous System)

Brain and spinal cord.

Synapse

Gap where chemicals pass a nerve signal.

DNA

Molecule carrying genetic information, with most human DNA found in the nucleus.

Gene

A section of DNA coding for a product.

Allele

A version of a gene.

Chromosome

A long DNA molecule.

Genotype

An organism's allele combination.

Phenotype

Observable characteristics.

Dominant allele

Allele expressed when one copy is present.

Recessive allele

Allele expressed when two copies are present.

Homozygous

Having two identical alleles.

Heterozygous

Having two different alleles.

Gamete

A sex cell.

Meiosis

Cell division making haploid cells, resulting in $4$ genetically different cells.

Fertilisation

Fusion of two gametes.

Human body cell chromosome count

$46$.

Human gamete chromosome count

$23$.

Mutation

A change in DNA that creates new alleles.

Sources of genetic variation

Mutations and sexual reproduction.

Punnett square

A diagram that shows possible offspring genotypes.

Evolution

Inherited change over generations.

Natural selection

Theory developed by Darwin and Wallace stating that better-adapted organisms reproduce more.

Adaptation

A feature helping survival or reproduction.

Genetic variation

Differences in inherited characteristics.

Extinction

When a species dies out.

Fossil

Preserved remains or traces of life that provide evidence of evolution.

Selective breeding

Choosing parents with desired traits, which carries a risk of reduced genetic diversity.

Genetic modification

Changing an organism's DNA.

GMO

A genetically modified organism.

Reasons to modify crops

To improve yield or pest resistance.

Plasmid

Small circular DNA in bacteria.

Vector (in genetic engineering)

Structure that carries DNA into cells.

Biodiversity