What determines a biological molecule’s shape and chemical properties?
The types and arrangement of its atoms.
AQA GCSE Combined Science: Trilogy (8464) — Biology — Higher · 4.8
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What determines a biological molecule’s shape and chemical properties?
The types and arrangement of its atoms.
How do a biological molecule’s shape and chemical properties influence its function?
They influence its interactions with other molecules, enabling it to perform roles in living organisms.
How can a change in a biological molecule’s structure change its function?
It can change the molecule’s interactions with other molecules.
What is an adaptation?
An inherited feature that makes an organism better suited to its environment and can increase its reproductive success there.
What are the three types of adaptation, and what does each involve?
How can natural selection make a population better adapted over generations?
It can increase the frequency of alleles associated with advantageous features.
How do adaptation and selection relate to evolution and the diversity of living organisms?
Together, they contribute to evolution and the diversity of living organisms.
What makes a cell in a complex multicellular organism specialised?
Its features are suited to a particular function, for example its shape or the abundance or arrangement of its cell structures.
How should you explain a specialised cell’s adaptation?
Link a specific feature of the cell to how it helps the cell perform its function.
What is a cell?
A basic living unit.
How are new cells produced?
By the division of existing cells.
How are cells, tissues, organs and organ systems organised in a multicellular organism?
Groups of cells work together to form tissues; different tissues work together to form organs; organs work together to form organ systems.
What is an organism?
An individual living thing made up of coordinated parts.
Under what condition does natural selection occur?
Individuals with different heritable phenotypes differ in survival or reproductive success.
How can selection pressures such as predation, disease and competition affect phenotypes?
They can favour phenotypes that provide an advantage in the prevailing conditions.
How are favourable alleles passed on through natural selection?
Individuals with advantageous phenotypes are more likely to reproduce and pass their favourable alleles to offspring.
How can natural selection cause evolution over generations?
Favourable alleles can increase in frequency in the population’s gene pool.
What is evolution?
A change in allele frequencies in a population over time.
What is evolution?
Change in the inherited characteristics of populations over generations.
What process can contribute to evolution?
Natural selection.
How can diverging populations descended from shared ancestors contribute to biodiversity?
They can give rise to different species.
What connects living organisms through their evolutionary history?
Common ancestry.
How does the recency of a common ancestor relate to how closely organisms are related?
Organisms with a more recent common ancestor are more closely related.
What is a population in ecology?
A group of organisms of the same species living in the same area at the same time.
What is a community in ecology?
Populations of different species living and interacting in an area.
What is an ecosystem?
A community and the non-living environment with which its organisms interact.
What is the relationship between humans and ecosystems?
Humans are part of ecosystems and can both influence and be affected by organisms and environmental conditions.
What does interdependence mean for organisms, including humans, in an ecosystem?
They depend on other organisms for resources or processes needed for survival and reproduction.
What are three ways organisms can depend on one another in an ecosystem?
For food, shelter or assistance with reproduction.
How can a change in one population affect an ecosystem community?
It can affect populations that depend on it, with effects extending through the community.
How do green plants and algae use carbon and hydrogen to make organic compounds in photosynthesis?
They fix carbon from carbon dioxide and combine it with hydrogen derived from water.
What energy transfer occurs during photosynthesis?
Light energy from the Sun is transferred into chemical energy stored in organic compounds.
What gas is released during photosynthesis?
Oxygen.
How does photosynthesis supply organic material to organisms?
It supports plants and algae and, directly or indirectly, many other organisms.
How does photosynthesis contribute to aerobic respiration?
It supplies much of the oxygen used in aerobic respiration.
What is cellular respiration?
A series of chemical reactions in living cells that breaks down organic fuel molecules and transfers energy into forms cells can use.
What does the energy transferred by cellular respiration support?
Other chemical reactions and processes needed to sustain life.
How can organisms obtain organic fuels for cellular respiration?
They can be made by photosynthetic organisms or obtained as food.
What happens to matter as it cycles through an ecosystem?
It is continually transferred between organisms and the non-living environment and reused, rather than permanently consumed.
What are the two ways organisms obtain substances in an ecosystem?
They take them up from their surroundings or obtain them by feeding.
Which three processes return substances to the air, water or soil?
Respiration, excretion and decomposition.
How do the routes taken by different chemicals through an ecosystem compare?
Different chemicals follow different routes.
What is an organism's phenotype?
Its observable characteristics.
What is an organism's genome?
Its complete set of genetic material.
How does an organism's genome influence its characteristics?
Through the information carried by its genes.
How can environmental conditions affect an organism's characteristics?
They can affect how characteristics develop or are expressed.
How are genetic and environmental influences related in determining phenotype?
Phenotype reflects their interaction, rather than being determined by either alone.