AQA COMBINED SCIENCE BIOLOGY GENERAL

What is a prokaryotic cell?

A prokaryotic cell is a simple cell type without a nucleus or membrane-bound organelles, such as bacteria.

What is the function of the nucleus in a eukaryotic cell?

The nucleus controls cell activities and contains genetic material (DNA).

Define cellular respiration.

Cellular respiration is the process of converting glucose and oxygen into energy (ATP), carbon dioxide, and water.

What is the role of chloroplasts in plant cells?

Chloroplasts are organelles that conduct photosynthesis, converting light energy into chemical energy.

What do enzymes do?

Enzymes act as catalysts to speed up chemical reactions without being consumed in the process.

What is diffusion?

Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.

How do you calculate magnification?

Magnification can be calculated by dividing the image size by the actual size of the object.

What are the main components of a cell membrane?

The cell membrane is primarily made up of a phospholipid bilayer, proteins, cholesterol, and carbohydrates.

List the levels of organization in biology, from smallest to largest.

Cell, tissue, organ, organ system, organism.

What is an antigen?

An antigen is a substance that triggers an immune response, typically found on the surface of pathogens.

Describe the function of red blood cells.

Red blood cells transport oxygen from the lungs to body tissues and carry carbon dioxide back to the lungs.

What is the purpose of a vaccine?

A vaccine stimulates the immune system to develop immunity against a specific pathogen without causing the disease.

Define homeostasis.

Homeostasis is the process of maintaining a stable internal environment in the body despite external changes.

What is the role of insulin in the body?

Insulin regulates blood glucose levels by facilitating the uptake of glucose into cells.

What are stomata and their function?

Stomata are small openings on plant leaves that allow gas exchange (CO2 in, O2 out) and transpiration.

What occurs during natural selection?

Natural selection is the process by which individuals with favorable traits are more likely to survive and reproduce.

Explain what homologous chromosomes are.

Homologous chromosomes are pairs of chromosomes, one from each parent, that are similar in shape and genetic content.

What is the difference between genotype and phenotype?

Genotype is the genetic makeup of an organism, while phenotype is the observable traits expressed by that genotype.

Describe what a food chain is.

A food chain is a linear sequence of organisms where each is eaten by the next one in the chain.

What is ecological succession?

Ecological succession is the process by which ecosystems change and develop over time, often following a disturbance.

Define biotic factors in an ecosystem.

Biotic factors are living components of an ecosystem, such as plants, animals, and microorganisms.

What does the term 'carrying capacity' refer to?

Carrying capacity is the maximum number of individuals of a species that an environment can sustain indefinitely.

What is a limiting factor for population growth?

A limiting factor is any resource or environmental condition that limits the growth, abundance, or distribution of a population.

Explain what a pathogen is.

A pathogen is an organism that causes disease, including bacteria, viruses, fungi, and parasites.

What is the purpose of a control group in an experiment?

A control group serves as a baseline to compare the effects of the independent variable in an experiment.

Describe the experiment for testing the effect of light intensity on photosynthesis.

The experiment often involves measuring the rate of photosynthesis by counting oxygen bubbles produced by a plant in varying light intensities.

What are the three main types of rocks in the rock cycle?

The three main rock types are igneous, sedimentary, and metamorphic rocks.

What is osmosis?

Osmosis is the diffusion of water molecules through a selectively permeable membrane from a dilute to a concentrated solution.

Define mutation.

A mutation is a change in the DNA sequence that can lead to alterations in protein function and traits.

Explain genetic variation.

Genetic variation refers to the differences in DNA sequences among individuals, which contribute to diversity in traits.

What is the role of decomposers in an ecosystem?

Decomposers break down dead organic matter, returning nutrients to the soil and maintaining ecosystem health.

What is meant by species richness?

Species richness is the number of different species present in an ecosystem.

How does photosynthesis benefit plants?

Photosynthesis allows plants to convert light energy into chemical energy (glucose) for growth and metabolism.

Explain what 'trophic levels' are.

Trophic levels represent the position of an organism in the food chain, ranging from producers to various levels of consumers.

What are antibodies?

Antibodies are proteins produced by the immune system that specifically target and neutralize pathogens.

What is biodiversity?

Biodiversity refers to the variety of life in a particular habitat or ecosystem, including species richness and genetic diversity.

Define evolution.

Evolution is the process through which species change over time through mechanisms like natural selection and genetic drift.

What role do ribosomes play in a cell?

Ribosomes are the sites of protein synthesis, translating messenger RNA into polypeptides.

What is the significance of the cell membrane's fluid mosaic model?

The fluid mosaic model describes the cell membrane as a flexible structure with various proteins embedded in a phospholipid bilayer.

Describe the process of transpiration in plants.

Transpiration is the movement of water through a plant from the roots to the leaves, ending in evaporation from leaf surfaces.

What determines the rate of transpiration?

The rate of transpiration is influenced by environmental factors such as temperature, humidity, wind speed, and light intensity.

What is a clone?

A clone is a genetically identical copy of an organism produced asexually.

Explain the concept of a food web.

A food web is a complex network of interconnected food chains showing how different organisms are related in terms of energy flow.

What is homeostatic regulation?

Homeostatic regulation maintains internal stability through feedback mechanisms, like temperature and pH balance.

Describe the structure and function of a neuron.

A neuron consists of a cell body, dendrites, and an axon, responsible for transmitting electrical signals throughout the body.

What types of interactions are found in symbiotic relationships?

Symbiotic relationships include mutualism, commensalism, and parasitism, each influencing the involved species differently.

What is a biome?

A biome is a large geographic biotic unit characterized by specific climate conditions, plants, and animals.

Define puffing in the context of cellular respiration.

Puffing, in the context of cellular respiration, refers to intermittent bursts of energy production through anaerobic respiration.

What is selective breeding?

Selective breeding is the process of choosing parent organisms with specific traits to produce desired offspring.

What is the role of the cell wall in plant cells?

The cell wall provides structural support and protection to plant cells and helps maintain cell shape.

Describe the stages of the cell cycle.

The cell cycle consists of interphase (G1, S, G2) and mitotic phase (mitosis and cytokinesis).

What is the importance of water in biological systems?

Water is essential for life, acting as a solvent, temperature regulator, and participant in metabolic reactions.

What factors can affect enzyme activity?

Enzyme activity can be affected by temperature, pH, substrate concentration, and inhibitors.

What is the difference between primary and secondary succession?

Primary succession occurs in lifeless areas (like after a volcanic eruption), while secondary succession occurs in previously inhabited areas (after events like fires).

Define fossilization.

Fossilization is the process by which organic materials are preserved over geological time, often transformed into rock.

What is a dominant allele?

A dominant allele is an allele that expresses its trait even in the presence of a recessive allele.

What is a recessive allele?

A recessive allele is an allele that only expresses its trait when two copies are present, one from each parent.

What is the difference between a habitat and a niche?

A habitat is where an organism lives, while a niche refers to its role in the ecosystem and how it obtains resources.

Explain what genetic drift is.

Genetic drift is the change in allele frequencies in a population due to random sampling, often having a greater effect in small populations.

What role do fungi play in ecosystems?

Fungi act as decomposers, breaking down dead organic matter and recycling nutrients back into the soil.

What is the significance of the carbon cycle?

The carbon cycle describes the movement of carbon through ecosystems, essential for life and regulating climate.

Define biodiversity hotspot.

A biodiversity hotspot is a biogeographic region with significant levels of plant endemism and experiencing habitat loss.

What is the purpose of the aseptic technique in microbiology?

The aseptic technique aims to prevent contamination during laboratory procedures to ensure valid results.

Describe two main types of plant transport tissue.

Xylem transports water and minerals from roots to leaves, while phloem transports sugars and nutrients throughout the plant.

What are the implications of climate change on ecosystems?

Climate change can lead to habitat destruction, altered species distributions, and increased extinction rates.

What is the role of the skeletal system in the human body?

The skeletal system provides structure, support, protection for internal organs, and facilitates movement.

What is a pedigree chart?

A pedigree chart is a diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors.

Explain what a biomolecule is.

Biomolecules are organic molecules that are essential for life, including carbohydrates, proteins, lipids, and nucleic acids.

What is osmoregulation?

Osmoregulation is the process by which organisms regulate water and electrolyte balance to maintain homeostasis.

What is the function of the immune system?

The immune system protects the body against pathogens through a complex network of cells, tissues, and organs.

Define desertification.

Desertification is the process by which fertile land becomes increasingly arid, often losing its vegetation and productivity.

What is the difference between biotic and abiotic factors?

Biotic factors are living components of an ecosystem; abiotic factors are non-living components like temperature and soil.

What are hormones?

Hormones are chemical messengers produced by glands that regulate various biological processes in the body.

Explain the significance of enzyme specificity.

Enzyme specificity refers to the ability of an enzyme to choose exact substrates from a group of similar chemical molecules.

What is the role of the plasma membrane?

The plasma membrane controls the movement of substances in and out of the cell, maintaining homeostasis.

Describe the process of mitosis.

Mitosis is a type of cell division that results in two genetically identical daughter cells, essential for growth and repair.

What is a chromosomal aberration?

A chromosomal aberration is a deviation from the normal chromosome number or structure, often leading to genetic disorders.

What are phylogenetic trees?

Phylogenetic trees represent the evolutionary relationships among various species based on genetic similarities and differences.

What is transgenic organism?

A transgenic organism is one that has been genetically engineered to contain a gene or genes from another organism.

What is the ecological significance of wetlands?

Wetlands are important ecosystems that provide habitat, flood protection, water filtration, and carbon storage.

Explain the role of the cortical region in plants.

The cortical region in plants provides structural support and storage for nutrients and water in roots.

What is the function of mitochondria?

Mitochondria are known as the powerhouses of the cell, producing ATP through cellular respiration.

Define the term angiosperm.

Angiosperms are flowering plants that produce seeds enclosed within a fruit.

What is chlorophyll and its role?

Chlorophyll is a green pigment in plants that captures light energy for photosynthesis.

Describe the role of ribosomes in protein synthesis.

Ribosomes read mRNA sequences and assemble amino acids into polypeptides to form proteins.

What is the significance of genetic diversity in populations?

Genetic diversity enhances a population's ability to adapt to changing environments and resist diseases.

What is the role of producers in an ecosystem?

Producers, mainly plants, convert light energy into chemical energy through photosynthesis, forming the base of food chains.

Define the greenhouse effect.

The greenhouse effect is the warming of Earth's surface due to trapped heat by greenhouse gases in the atmosphere.

What is antibiotic resistance?

Antibiotic resistance occurs when bacteria evolve to become resistant to the effects of medication that once killed them.

Explain what a biotechnological application is.

Biotechnological applications involve using living organisms or biological systems to develop products or processes for specific uses.

What is ecological footprint?

An ecological footprint measures the demand placed on Earth's ecosystems and the amount of natural resources consumed.

What is xenotransplantation?

Xenotransplantation is the transplantation of organs, tissues, or cells between different species.

Define genetic engineering.

Genetic engineering is the direct manipulation of an organism's DNA using biotechnology to alter its characteristics.

Explain the role of the amygdala.

The amygdala is a brain region involved in processing emotions, particularly fear and pleasure responses.

What are the three main types of graphs used in biology?

The three main types of graphs are bar graphs, line graphs, and pie charts, each used to represent different data types.

What is a keystone species?

A keystone species is one whose impact on its ecosystem is disproportionately large relative to its abundance.

Explain the role of sound waves in echolocation.

Echolocation is the process of using sound waves to determine the location and distance of objects, typically used by bats.

What is symbiosis?

Symbiosis is a close and long-term interaction between two different species, which can be beneficial, neutral, or harmful.

What are biomes categorized by?

Biomes are categorized by climate, vegetation, and the adaptations of organisms living in those areas.

Define the term 'clade' in biology.

A clade is a group of organisms that includes an ancestor and all descendants of that ancestor.