Biology basics
59 flashcards covering Biology basics for the ACT Science section.
Biology basics cover the fundamental concepts of life and living organisms, making it easier to understand the natural world around us. At its core, biology explores topics like cells and their functions, genetics and heredity, evolution through natural selection, and ecosystems including how organisms interact with their environment. These ideas form the building blocks for more advanced studies and help explain everyday phenomena, from plant growth to human health, giving you a solid foundation for scientific reasoning.
On the ACT Science section, biology questions typically appear in data interpretation, research summaries, or conflicting hypotheses passages, where you'll analyze graphs, experiments, or biological data. Common traps include misreading details in passages or confusing similar terms like mitosis and meiosis, so watch for subtle differences. Focus on understanding key processes, drawing conclusions from evidence, and applying basic concepts to new contexts, as the test emphasizes critical thinking over rote memorization.
A concrete tip: Practice identifying main ideas in biology passages to boost your speed and accuracy.
Terms (59)
- 01
Cell
The basic structural and functional unit of all living organisms, consisting of a membrane-bound compartment that contains genetic material and performs essential life processes.
- 02
Prokaryotic cell
A type of cell that lacks a nucleus and membrane-bound organelles, typically found in bacteria and archaea, and is generally smaller and simpler than eukaryotic cells.
- 03
Eukaryotic cell
A cell that has a nucleus enclosed within membranes and other membrane-bound organelles, found in plants, animals, fungi, and protists, allowing for more complex functions.
- 04
Nucleus
The organelle in eukaryotic cells that houses the cell's genetic material in the form of chromosomes and controls cellular activities by directing protein synthesis.
- 05
Mitochondrion
An organelle in eukaryotic cells responsible for producing energy in the form of ATP through cellular respiration, often called the powerhouse of the cell.
- 06
Chloroplast
An organelle found in plant cells and some protists that conducts photosynthesis, converting light energy into chemical energy stored as glucose.
- 07
Cell membrane
A semi-permeable barrier that surrounds the cell, regulating the passage of substances in and out to maintain internal conditions.
- 08
Cytoplasm
The gel-like substance within the cell membrane that contains organelles and is the site of many metabolic reactions.
- 09
DNA
Deoxyribonucleic acid, the molecule that carries genetic instructions for the development, functioning, and reproduction of all known living organisms.
- 10
Gene
A segment of DNA that contains the instructions for building a specific protein or RNA molecule, determining traits in organisms.
- 11
Chromosome
A structure made of DNA and proteins that contains many genes, found in the nucleus of eukaryotic cells and organized for cell division.
- 12
Photosynthesis
The process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water, producing oxygen as a byproduct.
- 13
Cellular respiration
The process by which cells break down glucose and other molecules to produce ATP for energy, typically involving oxygen in aerobic conditions.
- 14
Mitosis
A type of cell division that results in two identical daughter cells with the same number of chromosomes as the parent cell, used for growth and repair.
- 15
Meiosis
A specialized form of cell division that produces gametes with half the number of chromosomes, essential for sexual reproduction and genetic diversity.
- 16
Enzyme
A protein that acts as a biological catalyst, speeding up chemical reactions in cells without being consumed, by lowering the activation energy.
- 17
Protein
A large molecule composed of amino acid chains that performs a wide range of functions in organisms, including structural support and enzymatic activity.
- 18
Osmosis
The diffusion of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
- 19
Diffusion
The movement of particles from an area of higher concentration to an area of lower concentration, driven by random molecular motion, until equilibrium is reached.
- 20
Homeostasis
The ability of an organism or cell to maintain a stable internal environment despite changes in external conditions, such as temperature or pH.
- 21
Natural selection
A mechanism of evolution where organisms with traits better suited to their environment are more likely to survive and reproduce, leading to adaptation.
- 22
Evolution
The process by which populations of organisms change over generations through mechanisms like natural selection, resulting in new species.
- 23
Ecosystem
A community of living organisms interacting with each other and their physical environment, including both biotic and abiotic components.
- 24
Food chain
A linear sequence showing the flow of energy and nutrients in an ecosystem, from producers like plants to consumers and decomposers.
- 25
Food web
A complex network of interconnected food chains in an ecosystem, illustrating multiple feeding relationships among organisms.
- 26
Biodiversity
The variety of life in a particular habitat or on Earth, including genetic, species, and ecosystem diversity, which supports ecosystem stability.
- 27
Producer
An organism, such as a plant, that produces its own food through photosynthesis, forming the base of the food chain by converting sunlight into energy.
- 28
Consumer
An organism that obtains energy by eating other organisms, classified as herbivores, carnivores, or omnivores depending on their diet.
- 29
Decomposer
An organism, like bacteria or fungi, that breaks down dead organic matter, recycling nutrients back into the ecosystem.
- 30
Adaptation
A trait that enhances an organism's survival and reproduction in its specific environment, developed through natural selection over time.
- 31
Mutation
A change in the DNA sequence of an organism's genome, which can be harmful, neutral, or beneficial and is a source of genetic variation.
- 32
Allele
A variant form of a gene that occupies the same position on a chromosome and determines different expressions of a trait.
- 33
Dominant trait
A genetic trait that is expressed in the phenotype if at least one copy of the dominant allele is present, masking the recessive trait.
- 34
Recessive trait
A genetic trait that is only expressed in the phenotype when two copies of the recessive allele are present.
- 35
Punnett square
A grid used to predict the probabilities of different genotypes in offspring from a genetic cross between two individuals.
- 36
Symbiosis
A close and long-term interaction between two different biological species, which can be mutualistic, commensal, or parasitic.
- 37
Photosynthesis equation
The chemical formula 6CO2 + 6H2O + energy → C6H12O6 + 6O2, representing how plants convert carbon dioxide and water into glucose and oxygen.
- 38
Active transport
The movement of substances across a cell membrane against their concentration gradient, requiring energy from ATP.
- 39
pH scale
A measure from 0 to 14 that indicates the acidity or basicity of a solution, with 7 being neutral, below 7 acidic, and above 7 basic.
- 40
Acid
A substance that donates hydrogen ions in water, lowering the pH and often involved in biological processes like digestion.
- 41
Base
A substance that accepts hydrogen ions or donates hydroxide ions, raising the pH and helping maintain cellular functions.
- 42
Virus
A non-cellular infectious agent that replicates inside the cells of living hosts, consisting of genetic material surrounded by a protein coat.
- 43
Bacteria
Single-celled prokaryotic microorganisms that can be beneficial or harmful, playing key roles in decomposition and disease.
- 44
Fungus
A eukaryotic organism, like mushrooms or yeast, that absorbs nutrients from organic matter and can form symbiotic relationships.
- 45
Population
A group of individuals of the same species living in the same area at the same time, interacting and interbreeding.
- 46
Community
All the populations of different species living and interacting in a specific area, forming a complex web of relationships.
- 47
Biome
A large geographical area with distinct plant and animal communities adapted to similar environmental conditions, like deserts or forests.
- 48
Genetic drift
A random change in allele frequencies in a population over generations, especially significant in small populations.
- 49
Speciation
The process by which new species form, often due to geographical isolation or reproductive barriers that prevent interbreeding.
- 50
Mutualism
A symbiotic relationship where both species benefit, such as bees pollinating flowers while obtaining nectar.
- 51
Parasitism
A symbiotic relationship where one organism benefits at the expense of the host, often causing harm, like a tick feeding on a dog.
- 52
Commensalism
A symbiotic relationship where one organism benefits and the other is neither helped nor harmed, like barnacles on a whale.
- 53
Tropism
The growth or turning movement of a plant in response to an environmental stimulus, such as light or gravity.
- 54
Fermentation
An anaerobic process where cells convert sugars into acids, gases, or alcohol to generate energy without oxygen.
- 55
Aerobic respiration
Cellular respiration that requires oxygen to break down glucose completely into carbon dioxide and water, producing maximum ATP.
- 56
Anaerobic respiration
A form of respiration that occurs without oxygen, producing less ATP and often resulting in byproducts like lactic acid.
- 57
Common trap in osmosis
Students often confuse osmosis with diffusion, but osmosis specifically involves water moving across membranes, not other solutes.
- 58
Worked example of Punnett square
For a cross between two heterozygous parents (Aa x Aa), the Punnett square shows a 75% chance of dominant phenotype and 25% recessive.
- 59
Hormone
A chemical messenger produced by glands that travels through the bloodstream to regulate functions like growth and metabolism in organisms.