BIO120 Unit 1 Review – The Nature of Science and Biology

A set of Question-and-Answer flashcards covering core topics from Unit 1 notes on biology, the scientific method, macromolecules, cells, and basic biochemistry.

Made of cells, use energy, maintain homeostasis, respond to environment, grow & develop, reproduce, evolve, contain DNA.

What are the characteristics of life as listed in BIO120 Unit 1?

Atoms → molecules → organelles → cells → tissues → organs → organ systems → organisms → populations → communities → ecosystems → biosphere.

What is the correct sequence of the levels of biological organization from smallest to largest?

Testable, falsifiable, based on observations, and capable of making predictions.

What are the main characteristics of a scientific hypothesis?

Only one independent variable is changed; all other variables are controlled; includes a control group and an experimental group.

What defines a controlled experiment?

Random assignment, large sample size, double-blind studies, and use of placebos.

How is bias eliminated in experiments?

Science is tentative; new evidence can change conclusions; we only support findings, not prove them.

Why can’t science prove findings beyond doubt?

Primary = original research; Secondary = summaries or reviews.

What is the difference between primary and secondary sources?

Scientific theory is a well-supported explanation; everyday theory is a guess.

How does a scientific theory differ from an everyday theory?

Neither participants nor researchers know who receives the treatment.

What is a double-blind experiment?

They show relationships or associations, not causation.

What do correlation studies show?

Correlation does not imply causation; a relationship does not prove that one variable causes the other.

What is the difference between correlation and causation?

The results are unlikely to have occurred by chance.

What does statistical significance (p < 0.05) indicate?

Variables kept the same in all groups to ensure valid comparisons.

What are constant/controlled variables?

Observing and recording phenomena without testing hypotheses or manipulating variables.

What are descriptive studies?

A group that receives no treatment and serves as a baseline.

What is a control group?

A group that receives the treatment being tested.

What is an experimental group?

The variable intentionally changed by the experimenter.

What is an independent variable?

The variable that is measured and observed.

What is a dependent variable?

The concentration of hydrogen ions (H+) in a solution; affects enzymes and cell processes.

What does pH measure?

Polar; cohesion; adhesion; high specific heat; expands when frozen; universal solvent.

What are the key properties of water relevant to biology?

Polar molecules have charged regions; nonpolar molecules do not.

What is the difference between polar and nonpolar molecules?

Water-loving; readily interacts with water.

What does hydrophilic mean?

Water-fearing; tends to repel or avoid water.

What does hydrophobic mean?

Molecules with both hydrophilic and hydrophobic parts.

What does amphipathic mean?

Contains carbon and hydrogen.

What does the term organic mean in biology?

Monomer: glucose; Polymers: glycogen (animals), starch (plants).

What is the carbohydrate monomer and a common polymer in animals?

Glycogen (animal energy storage), starch (plant energy storage), cellulose (plant cell walls), chitin (exoskeletons), peptidoglycan (bacterial cell walls).

What are the main carbohydrate polymers and their roles?

Monomer: amino acids; Polymer: polypeptides; Function: structure, enzymes, antibodies, movement.

What are the monomer, polymer, and function of proteins?

Lipids are not polymers. Major types: triglycerides (long-term energy), steroids (hormones/cholesterol), phospholipids (membranes), waxes (waterproofing).

Are lipids polymers? If not, what are their major categories and roles?

Saturated fats are typically animal fats, solid at room temperature; unsaturated fats are typically plant fats, bent tails, liquid.

What is the difference between saturated and unsaturated fats?

Long-term energy storage.

What is the role of triglycerides?

Steroids are lipids that include hormones and cholesterol.

What are steroids and why are they important?

Main components of cell membranes; amphipathic with hydrophilic heads and hydrophobic tails.

What are phospholipids and what is their role?

Waterproofing and protective coatings.

What are waxes used for?

Nucleotide.

What is the monomer of nucleic acids?

DNA and RNA; DNA stores genetic information, RNA helps express it.

What are the polymers of nucleic acids and their functions?

DNA: deoxyribose, bases A T C G, double-stranded, very stable; RNA: ribose, bases A U C G, usually single-stranded, less stable.

What are the key differences between DNA and RNA?

All life is made of cells; the cell is the basic unit of life; all cells arise from existing cells.

What is the Cell Theory?

Cell membrane, cytoplasm, DNA, ribosomes.

What do all cells have?

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have a nucleus and organelles.

What is the difference between prokaryotes and eukaryotes?

Plants have cell walls, chloroplasts, and a large central vacuole; animals lack these features.

What distinguishes plant cells from animal cells?

Holds DNA and controls cell activities.

What is the nucleus responsible for in a cell?

Synthesis of proteins.

What is the ribosome’s role?

Cellular respiration to produce ATP.

What is the mitochondrion’s function?

Site of photosynthesis in plants.

What is the chloroplast’s purpose?

Breaks down waste materials and cellular debris.

What is the lysosome’s function?

Rigid support for plant (and some bacterial and fungal) cells.

What is the cell wall’s role?

Cell structure and movement.

What is the cytoskeleton responsible for?

Phospholipid bilayer that controls what enters and exits the cell.

What is the cell membrane’s basic structure and role?

Respiration: breaks down glucose to release energy; Digestion: breaks down food into small molecules; Metabolism: all chemical reactions in the body.

What are respiration, digestion, and metabolism?

Respiration: glucose, oxygen, enzymes; Digestion: enzymes, acid, water; Metabolism: water, calories, enzymes.

What are the requirements for respiration, digestion, and metabolism?

Glucose is stored energy; ATP is usable energy for cellular work.

What is the difference between glucose and ATP in cellular energy?

Proteins that speed up reactions without being consumed; affected by temperature, pH, substrate concentration, and cofactors/coenzymes.

What are enzymes and what affects their activity?

Cofactors are inorganic helpers (metal ions); coenzymes are organic helpers (vitamins).

What are cofactors and coenzymes?

Reaction rate increases with temperature up to an optimum, then enzymes can denature at high temperatures.

How does temperature affect enzyme activity?

Each enzyme has an optimal pH; extreme pH can denature enzymes.

How does pH affect enzyme activity?

Increasing substrate concentration raises reaction rate until enzymes become saturated.

What is the effect of substrate concentration on enzyme activity?