A-Level Biology Flashcards

Flashcards for A-Level Biology review.

Monomers

Smaller units from which larger molecules are made.

Polymers

Molecules made from a large number of monomers joined together.

Examples of Monomers

Monosaccharides, amino acids, and nucleotides.

Condensation Reaction

Joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.

Hydrolysis Reaction

Breaks a chemical bond between two molecules and involves the use of a water molecule.

Monosaccharides

The monomers from which larger carbohydrates are made.

Common Monosaccharides

Glucose, galactose, and fructose.

Disaccharides

Formed by the condensation of two monosaccharides.

Maltose

Formed by condensation of two glucose molecules.

Sucrose

Formed by condensation of a glucose molecule and a fructose molecule.

Lactose

Formed by condensation of a glucose molecule and a galactose molecule.

Glycogen and Starch

Formed by the condensation of many glucose units (alpha-glucose).

Cellulose

Formed by the condensation of beta-glucose.

Triglycerides

Formed by the condensation of one molecule of glycerol and three molecules of fatty acid.

Phospholipids

Formed when one of the fatty acids of a triglyceride is substituted by a phosphate-containing group.

Amino Acids

The monomers from which proteins are made.

Peptide Bond

Formed by the condensation of two amino acids.

Dipeptides

Formed by the condensation of two amino acids.

Polypeptides

Formed by the condensation of many amino acids.

Enzyme

Lowers the activation energy of the reaction it catalyses.

DNA (Deoxyribonucleic Acid)

Holds genetic information; polymer of nucleotides containing deoxyribose, a phosphate group, and one of the organic bases adenine, cytosine, guanine, or thymine.

RNA (Ribonucleic Acid)

Transfers genetic information; polymer of nucleotides containing ribose, a phosphate group, and one of the organic bases adenine, cytosine, guanine, or uracil.

ATP (Adenosine Triphosphate)

A nucleotide derivative formed from a molecule of ribose, a molecule of adenine, and three phosphate groups.

ATP Hydrolase

Catalyzes the hydrolysis of ATP to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi).

ATP Synthase

Catalyzes the condensation of ADP and Pi to resynthesise ATP during photosynthesis or respiration.

Structures of Eukaryotic Cells

Cell-surface membrane, nucleus, mitochondria, chloroplasts, Golgi apparatus and Golgi vesicles, lysosomes, ribosomes, rough endoplasmic reticulum and smooth endoplasmic reticulum, cell wall, cell vacuole.

Differenced of Prokaryotic Cells from Eukaryotic Cells

Cytoplasm that lacks membrane-bound organelles, smaller ribosomes, no nucleus (single circular DNA molecule free in cytoplasm), cell wall contains murein.

Structure of Virus Particles

Genetic material, capsid, and attachment protein.

Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

Binary Fission in Prokaryotic Cells

Duplication of circular DNA and of plasmids, division of the cytoplasm to produce two daughter cells.

Movement Across Membranes

Simple diffusion, facilitated diffusion, osmosis, active transport, co-transport.

Cell Surface Molecules

Proteins that enable the immune system to identify pathogens, cells from other organisms, abnormal body cells, and toxins.

Antigen

A foreign molecule that triggers an immune response.

Phagocytosis

The engulfing and digestion of pathogens by phagocytes which are then destroyed by lysozymes.

Cellular Response

Response of T lymphocytes to a foreign antigen.

Helper T Cells (TH Cells)

Stimulate cytotoxic T cells, B cells, and phagocytes.

Humoral Response

Response of B lymphocytes to a foreign antigen, clonal selection, and the release of monoclonal antibodies.

Antibody

Protein produced by B lymphocytes in response to a specific antigen.

Antigen-Antibody Complex Formation

Agglutination and phagocytosis of bacterial cells.

Artificial Active Immunity

Vaccines.

Artificial Passive Immunity

Monoclonal Antibodies

Monoclonal Antibodies

Used in targeting medication to specific cell types and in medical diagnosis.

Exchange of substances

The internal environment of a cell or organism is different from its external environment; exchange of substances takes place at exchange surfaces.

Adaptations of gas exchange surfaces

Tracheae, tracheoles, spiracles. gill lamellae and filaments. mesophyll and stomata. alveoli bronchioles, bronchi, trachea and lungs.

Digestion in Mammals

Amylases, membrane-bound disaccharidases. Lipase, bile salts. Endopeptidases, exopeptidases and membrane-bound dipeptidases.

Mass transport in animals

Haemoglobin.

Mass transport in plants (water)

Xylem

Mass transport in plants (organic substances)

Phloem.

Gene

A section of DNA located at a particular site on a DNA molecule (locus) that carries the coded genetic information determining amino acid sequence during protein synthesis.

Genome

The complete set of genes in a cell.

Proteome

The full range of proteins that a cell is able to produce.

Transcription

Production of mRNA from DNA by RNA polymerase.

Translation

Production of polypeptides from the sequence of codons carried by mRNA using ribosomes, tRNA, and ATP.

Gene Mutations

Base deletion and base substitution.

Meiosis

When two nuclear divisions result in the formation of four haploid daughter cells from a single diploid parent cell, and genetically different daughter cells result from independent segregation of homologous chromosomes and crossing over.

Genetic Diversity

The number of different alleles of genes in a population.

Natural Selection

New alleles of a gene arise, some may be beneficial and lead to increased reproductive success in certain environments, advantageous allele is inherited, increases in frequency.

Species

Two organisms belong to the same if they are able to produce fertile offspring.

Phylogenetic Classification System

Attempts to arrange species into groups based on evolutionary origins and relationships (phylogeny) hierarchical with no overlap, groups are called taxa.

Taxa Hierarchy

Domain, kingdom, phylum, class, order, family, genus, and species.

Species Richness

A measure of the number of different species in a community.

Index of Diversity

A description of the relationship between the number of species in a community and the number of individuals in each species.

Light-Dependent Reaction

Chlorophyll absorbs light, energy conserved in ATP and reduced NADP, photolysis of water produces protons, electrons, and oxygen.

Light-Independent Reaction

Uses reduced NADP to form a simple sugar and requires ATP hydrolysis.

Glycolysis

Phosphorylation of glucose, production of triose phosphate, oxidation of triose phosphate to pyruvate with net gain of ATP and reduced NAD.

Aerobic Respiration

Pyruvate is oxidised to acetate, acetate combines with coenzyme A, acetylcoenzyme A reacts with a four-carbon molecule, Krebs cycle reactions, synthesis of ATP by oxidative phosphorylation.

Gross Primary Production (GPP)

The chemical energy store in plant biomass.

Net Primary Production (NPP)

The chemical energy store in plant biomass after respiratory losses to the environment have been taken into account.

Nutrient Cycles

Saprobionts, mycorrhizae, bacteria (saprobiotic nutrition, ammonification, nitrification, nitrogen fixation, denitrification).

Homeostasis

It's the maintenance of a stable internal environment

Plant Responses

Indoleacetic acid (IAA) on cell elongation in roots and shoots. Gravitropism and phototropism.

Simple Responses in Mobile Organisms

Taxes and kineses.

Stimulus

A change in the internal or external environment.

Receptors

Responds only to specific stimuli, stimulation leads to generator potential

Heart Rate Control

Myogenic stimulation

Resting Potential

differential membrane permeability, electrochemical gradients, movement of sodium and potassium ions.

Action Potential

Changes in membrane permeability lead to depolarisation and generation of action potential

Factors Affecting Speed of Conductance

Myelination, axon diameter, temperature.

Skeletal Muscle

Muscles acting in antagonistic pairs.

Importance of Homeostasis

Stable core temperature and stable blood pH in relation to enzyme activity, stable blood glucose concentration.

Blood Glucose Concentration Control

Factors that influence blood glucose concentration, liver's role in glycogenesis, glycogenolysis, and gluconeogenesis, action of insulin and glucagon, second messenger model, causes of types I and II diabetes.

Blood Water Potential Control

Role of hypothalamus, posterior pituitary, and antidiuretic hormone (ADH).

Homeostasis in Mammals

Involves physiological control systems to maintain the internal enviornment within restricted limits.

Diplod Organisms

In a diploid organism, the alleles at a specific locus may be either homozygous or heterozygous.

Genotype

The genetic constitution of an organism.

Phenotype

Expression of genetic constitution and its interactions with the enviornment.

Hardy-Weinberg equation

Where p is the frequency of one (usually dominant) allele and q is the frequency of the other allele.

Tumours

The main characteristics are that they are benign and malignant.

Eukaryotic Cells that can divide show a cell cycle

Totipotent, pluripotent, multipotent, unipotent.