AQA GCSE Combined Science: Trilogy 8464 Biology Revision

Flashcards for AQA GCSE Combined Science: Trilogy 8464 Biology Revision

What does the command word 'State, give, name, write down' mean?

Short answer only and does not require an explanation.

What does the command word 'Describe' mean?

Recall facts, events or process in an accurate way.

What does the command word 'Describe (graphs)' mean?

Identify the pattern in the graph and use numbers from the graph to make this clear.

What does the command word 'Describe (practical)/Plan' mean?

Write the method for the practical or the results that you would expect to see.

What does the command word 'Determine' mean?

Use given data or information to obtain and answer.

What does the command word 'Explain' mean?

Make something clear or state the reasons for something happening. You will need to state what is happening and then say why it happens.

What does the command word 'Evaluate' mean?

Use the information supplied and your own knowledge to consider the evidence for and against a point. You may also be required to include a justified conclusion.

What does the command word 'Compare' mean?

Describe the similarities and/or differences between things. Avoid writing about just one.

What does the command word 'Sketch' mean?

Draw approximately.

What features do eukaryotic cells have?

Plant and animal cells (eukaryotic cells) have genetic material enclosed in a nucleus to control the activity of the cell, a cell membrane to control what enters and exits the cell, and cytoplasm to allow reactions to take place.

What features do prokaryotic cells have?

Bacterial cells (prokaryotic cells) are much smaller in comparison. The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids. They also have cytoplasm, a cell membrane and a cell wall to provide strength and support to the cell.

What parts do most animal cells have?

nucleus, cytoplasm, a cell membrane, mitochondria, ribosomes

What additional parts do plant cells have?

chloroplasts, a permanent vacuole, a cell wall

What is the function of the Nucleus?

Controls the activities of the cell.

What is the function of the Cytoplasm?

Where chemical reactions take place.

What is the function of the Cell membrane?

Controls what enters and exits the cell.

What is the function of the Mitochondria?

Carries out aerobic respiration, which releases energy for the cell.

What is the function of the Ribosomes?

Carries out protein synthesis by joining many amino acids.

What is the function of the Chloroplasts?

Absorbs light for photosynthesis.

What is the function of the Vacuole?

Provides support to the cell.

What is the function of the Cell wall?

Strengthens the cell.

Define the term ‘stem cell’.

It is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

What is diffusion?

It is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

What is osmosis?

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

What is active transport?

Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.

How are living things organised?

Cells are the basic building blocks of all organisms. A tissue is a group of cells with a similar structure and function. Organs are aggregations of tissues performing specific functions. Organs are organised into organ systems, which work together to form organisms.

What is the function of the heart?

The heart is an organ that pumps blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs where gas exchange takes place. The left ventricle pumps blood around the rest of the body.

What is the function of the lungs?

The lungs are specialised organs adapted to allow for efficient gas exchange. They have a large surface area: volume ratio to ensure that gas exchange can occur at a high rate.

What is photosynthesis?

Photosynthesis is an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light to produce glucose.

What is cellular respiration?

Cellular respiration is an exothermic reaction which is continuously occurring in living cells. Respiration releases the energy needed for living processes.

What is metabolism?

Metabolism is the sum of all reactions in a cell or the body.

What is homeostasis?

Homeostasis is the regulation of the conditions inside a cell or organism.

What does the nervous system do?

The nervous system enables humans to react to their surroundings and to coordinate their behaviour.

What is the endocrine system?

The endocrine system is composed of glands which secrete hormones directly into the bloodstream. The blood carries the hormone to a target organ where it produces an effect.

What are chromosomes?

The nucleus of a cell contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes. In body cells the chromosomes are normally found in pairs.

What is mitosis and the cell cycle?

Cells divide in a series of stages called the cell cycle. During the cell cycle, the genetic material is doubled and then divided into two genetically identical daughter cells. Mitosis is important in the growth, repair and development of multicellular organisms.

What is cancer?

Cancer is the result of changes in cells that lead to uncontrolled growth and division. Tumours can be malignant or benign. Both genetic factors and lifestyle choices can affect an individual’s likelihood of developing cancer.

What is DNA?

The genetic material in the nucleus is composed of a chemical called DNA. DNA is a polymer made up of two strands forming a double helix. The DNA is contained in structures called chromosomes.

What is variation?

There is extensive variation within a population of a species. The phenotype (observable characteristics) of an organism is affected by both genetics and the environment. Mutations occur continuously. Very rarely, a mutation will lead to a new characteristic. If the new characteristic is advantageous it can lead to a change in the species.

What is evolution?

The theory of evolution states that all species of living things have evolved from simple life forms that first developed more than three billion years ago. Evolution is a change in the inherited characteristics of a population over time through a process of natural selection, which may result in the formation of a new species. If two populations of one species become so different that they are no longer able to interbreed to produce fertile offspring, they have formed two new species.

How are living things classified?

Traditionally living things have been classified into groups depending on their structure and characteristics in a system developed by Carl Linnaeus. As evidence of internal structures become more developed due to improvements in microscopes, and the understanding of biochemical processes progressed, new models of classification were proposed. Due to evidence available from chemical analysis there is now a three domain system developed by Carl Woese.

What is a community?

An ecosystem is the interaction of a community of living organisms with the non-living parts of their environment. Organisms require a supply of materials from their surroundings and other living organisms there. Plants compete with each other for light, space, water and mineral ions. Animals compete with each other for food, mates and territory. Interdependence means that communities of species depend on other species for food, shelter, pollination, water etc. If one species is removed, it can affect the whole community. In a stable community, all the species and environmental factors are in balance and population sizes remain fairly constant.

What are adaptations?

Adaptations are features that enable them to survive in the conditions in which they normally live. These adaptations may be structural, behavioural or functional. Extremophiles live in environments that are very extreme, such as at high temperature, pressure, or salt concentration.

What are levels of organism?

Photosynthetic organisms (plants and algae) are the producers of biomass for life on Earth. Transects and quadrats are used to determine the distribution and abundance of species in an ecosystem. All organisms are part of a food chain.

What is biodiversity?

Biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem. A great biodiversity ensures the stability of ecosystems by increasing the availability of food and shelter for organisms. Many human activities, such as deforestation, are reducing biodiversity. Only recently have measures been taken to try and stop this reduction. One way is carbon sequestration.

What is Land use?

Land pollution can occur from landfill and from toxic chemicals. Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste. Peat bogs are wetland areas made up of partially decomposing material. Peat is used as garden compost because it contains a high concentration of mineral ions. The destruction of peat bogs results in a loss of biodiversity. The decay or burning of peat releases carbon dioxide into the environment.

What is Deforestation?

Large-scale deforestation in tropical areas has occurred in order to provide land for cattle and rice fields, and grow crops for biofuel.

How can we maintain biodiversity?

Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity. These include breeding programmes for endangered species, protection and regeneration of rare habitats, re-introduction of hedgerows in agricultural areas where farmers grow only one type of crop, reduction of deforestation and carbon dioxide emissions and recycling initiatives.

What is the human digestive system?

The digestive system is an organ system where several organs work together to absorb and digest food. Digestive enzymes convert large insoluble molecules into smaller soluble ones so they can be absorbed into the blood stream.

What are pathogens?

Pathogens are microorganisms that can cause disease. They can infect plants or animals and can be spread by direct contact, water or air.

What is vaccination?

Spread of pathogens can be reduced by vaccinating a large amount of the population. A vaccine prevents an individual becoming infected with and spreading a specific pathogen. Vaccinations work by introducing small amounts of dead/inactive pathogens into the body causing the white blood cells to respond.

What is global warming?

Global warming is the observed increase in the average surface temperature due to the effect of greenhouse gases. Increasing levels of the two main greenhouse gases, carbon dioxide and methane, are contributing to global warming.