Comprehensive Biology: Scientific Method, Cell Structure, and Biochemistry

What are the 6 steps of the scientific method in order?

1. Observation 2. Question 3. Research 4. Hypothesis 5. Experiment 6. Conclusion

What is anecdotal evidence?

Evidence based on personal observations or experiences rather than controlled scientific testing.

What is scientific evidence?

Evidence gathered through systematic observation, measurement, and experimentation.

What is a peer-reviewed article?

A scientific article evaluated by other experts before publication.

What is a scientific hypothesis?

A statement that is testable and falsifiable.

What is a controlled experiment?

An experiment designed to test one factor while controlling other variables.

What is a control group?

The group receiving a placebo or no treatment; it provides a comparison baseline.

What is a placebo?

A fake treatment used as a comparison with the experimental treatment.

What is the independent variable?

The factor the researcher deliberately changes or manipulates.

What is the dependent variable?

The measured result of an experiment.

What is homeostasis?

Maintaining a stable internal environment despite changes in the outside environment.

What does growth mean as a characteristic of life?

An increase in size over time.

What does reproduction mean as a characteristic of life?

The ability of organisms to produce offspring for the next generation.

What is a response to stimuli?

An organism's ability to sense and react to environmental changes.

What does obtaining energy mean as a characteristic of life?

Organisms must obtain and use energy to maintain life.

What is an autotroph?

An organism that makes its own food/energy, such as a plant using photosynthesis.

What is a heterotroph?

An organism that obtains nutrition by eating other organisms.

What is matter?

Anything that has mass and takes up three-dimensional space.

What is an element?

A chemically pure substance that cannot be broken down into simpler substances.

What is an atom?

The smallest unit of an element that retains its unique properties.

What are the 3 main subatomic particles?

Protons, neutrons, and electrons.

What is the charge of a proton?

Positive (+).

What is the charge of a neutron?

Neutral (no charge).

What is the charge of an electron?

Negative (−).

Where are protons and neutrons located?

In the nucleus at the center of the atom.

Where are electrons located?

Around the nucleus in distinct electron shells.

What is the atomic number?

The number of protons in an atom's nucleus.

What is atomic mass?

The total number of protons and neutrons in an atom.

How many electrons can the innermost electron shell hold?

2 electrons.

How many electrons can the outermost shell hold?

Up to 8 electrons.

Why are outer-shell electrons important?

They determine how an atom bonds with other elements.

What is a covalent bond?

A bond formed when atoms share electrons.

What is a polar covalent bond?

A covalent bond where electrons are shared unequally.

What is an ionic bond?

A bond formed by attraction between oppositely charged ions.

What is a cation?

A positively charged ion formed when an atom loses an electron.

What is an anion?

A negatively charged ion formed when an atom gains an electron.

What is a hydrogen bond?

A special attraction between partially positive and negative regions of molecules.

What are the 4 major biological macromolecules?

Carbohydrates, proteins, lipids, and nucleic acids.

What are carbohydrates made of?

Repeating sugar units called monosaccharides.

What are proteins made of?

Repeating amino acid subunits.

What are lipids?

Hydrophobic molecules that do not contain repeating monomers and do not mix with water.

What are nucleic acids made of?

Repeating nucleotide subunits; examples are DNA and RNA.

What is the phospholipid bilayer?

A membrane made of phospholipids with hydrophilic heads outward and hydrophobic tails inward.

What does hydrophilic mean?

Water-loving; attracted to or interacts with water.

What does hydrophobic mean?

Water-fearing; does not mix well with water.

What is the pH scale?

A 0-14 scale that measures how acidic or basic a solution is.

What is the pH of pure water?

7, which is neutral.

What is an acid?

A substance with a pH below 7 and more H+ ions.

What is a base?

A substance with a pH above 7 and more OH− ions.

What is the main difference between prokaryotic and eukaryotic cells?

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

What does the nucleus do?

Stores DNA, the cell's genetic instructions.

What does the rough ER do?

Helps produce proteins; ribosomes are attached to it.

What does the smooth ER do?

Produces lipids and lacks ribosomes.

What does the Golgi apparatus do?

Modifies, packages, and transports proteins using vesicles.

What do lysosomes do?

Break down worn-out cell components so materials can be recycled.

What do mitochondria do?

Extract energy from food and convert it into ATP.

What do chloroplasts do?

Carry out photosynthesis and convert solar energy into chemical energy.

What is diffusion?

Movement of small molecules from high to low concentration without energy.

What is osmosis?

Diffusion of water across a membrane.

What is facilitated transport?

Movement of larger molecules through transport proteins from high to low concentration; no energy.

What is active transport?

Movement through transport proteins from low to high concentration; requires energy.

What organelles are explained by the endosymbiosis theory?

Mitochondria and chloroplasts.