Biology exam prep all chapter

Biology

The study of life and living organisms

Organism

A living thing made up of one or more cells that carries out life functions

Homeostasis

The internal balance within the systems of living organisms that must be kept stable in order to maintain life

Cell

The basic structural and functional unit of all living things

Metabolism

The sum of the chemical processes that an organism uses to get energy from food to grow and function

Model

A representation used to explain a scientific concept or process

Scientific theory

A well-supported explanation of natural phenomena based on repeated evidence and experimentation

Independent variable

The variable that is changed by the scientist in an experiment

Dependent variable

The variable that is measured or observed in response to the independent variable

Control group

The group in an experiment that is not exposed to the independent variable; used for comparison

Constants

Factors in an experiment that are kept the same to ensure a fair test

Qualitative data

Data based on observed qualities or descriptions (color, shape, behavior)

Quantitative data

Data based on numerical measurements (length, mass, temperature)

Characteristics of life

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

Levels of biological organization (organism)

Cell to Tissue to Organ to Organ System to Organism

Levels of biological organization (ecosystem)

Population to Community to Ecosystem to Biome to Biosphere

Conservation

The careful management and protection of natural resources

Environmentalism

A movement focused on protecting the environment from harm

Biotic factors

Living parts of an ecosystem (plants, animals, bacteria)

Abiotic factors

Nonliving aspects of an ecosystem (light, water, air, temperature, humidity)

Atom

The building block of matter; the smallest particle of an element

Proton

Positively charged subatomic particle found in the nucleus

Neutron

Neutral (no charge) subatomic particle found in the nucleus

Electron

Negatively charged subatomic particle found in the electron cloud

Atomic number

Number of protons in the nucleus; unique to each element

Mass number

Number of protons plus neutrons in the nucleus

Element

A form of matter that contains only one type of atom (example: H)

Compound

A substance with two or more elements bonded with shared electrons (example: H2O)

Mixture

A physical combination of substances that can be separated (example: trail mix)

Solution

A type of mixture in which one substance is dissolved in another (example: sweet tea)

Cohesion

The attraction of water molecules to each other

Adhesion

The attraction of water to other substances

Carbohydrates

Macromolecule that provides energy; made of C, H, O (example: glucose, starches, sugars)

Lipids

Macromolecule that stores energy long-term; made of C, H, O (example: fats, oils)

Proteins

Macromolecule that builds muscles, hair, blood, and skin; made of amino acids (C, H, O, N)

Nucleic acids

Macromolecule that carries genetic information; made of nucleotides (DNA, RNA)

Enzymes

Proteins that speed up chemical reactions (catalysts) in cells

Factors affecting enzymes

Temperature, pH, and substrate concentration affect how enzymes work

1st Law of Thermodynamics

Energy cannot be created or destroyed, only transferred or transformed

Cell Theory

1) All living things are made of cells, 2) Cells are the basic unit of life, 3) All cells come from preexisting cells

Prokaryotic cell

Cell that lacks a true nucleus and membrane-bound organelles (example: bacteria)

Eukaryotic cell

Cell that has a true nucleus and membrane-bound organelles (example: plant, animal cells)

Plant cell unique features

Has cell wall, chloroplasts, and a large central vacuole

Animal cell unique features

No cell wall or chloroplasts; has lysosomes and centrosomes

Nucleus

Organelle that controls the cell and contains DNA

Ribosomes

Organelles that make proteins

Mitochondria

Powerhouse of the cell; performs cellular respiration to make ATP

Chloroplasts

Organelle in plant cells where photosynthesis occurs

Cell membrane

Semi-permeable barrier that controls what enters and leaves the cell

Cell wall

Rigid outer layer in plant cells made of cellulose that provides structure

Vacuole

Storage organelle for water, nutrients, and waste (large in plant cells)

Golgi apparatus

Modifies, packages, and ships proteins out of the cell

Endoplasmic reticulum

Network that transports materials throughout the cell; rough ER has ribosomes, smooth ER does not

Lysosomes

Organelle that contains digestive enzymes to break down waste (found in animal cells)

Cell membrane structure

Phospholipid bilayer with embedded proteins (semi-permeable)

Passive transport

Movement of molecules across a membrane WITHOUT using energy (ATP)

Diffusion

Movement of particles from high to low concentration (spread out)

Osmosis

Diffusion of WATER across a semi-permeable membrane

Facilitated diffusion

Type of passive transport using protein channels to help molecules cross the membrane

Active transport

Movement of molecules across a membrane that REQUIRES energy (ATP)

Why active transport needs energy

Because it moves molecules AGAINST the concentration gradient (low to high)

Photosynthesis equation

6H2O + 6CO2 + light energy -> C6H12O6 + 6O2

Cellular respiration equation

C6H12O6 + 6O2 -> 6H2O + 6CO2 + energy (ATP)

Where photosynthesis occurs

Chloroplasts in plant cells

Where cellular respiration occurs

Mitochondria of all eukaryotic cells

Light-dependent phase

First stage of photosynthesis; absorbs light energy and produces ATP and NADPH (occurs in thylakoids)

Light-independent phase (Calvin cycle)

Second stage of photosynthesis; uses ATP and NADPH to make glucose from CO2 (occurs in stroma)

ATP

Adenosine triphosphate; the energy currency of the cell that stores and releases energy

Aerobic respiration

Cellular respiration that REQUIRES oxygen; produces about 36 ATP

Anaerobic respiration

Cellular respiration that does NOT require oxygen; produces only 2 ATP

Fermentation

Anaerobic breakdown of sugars to pyruvate, then either to lactic acid OR alcohol and CO2

Lactic acid fermentation

Occurs in muscle cells during intense exercise; causes muscle cramping

Alcoholic fermentation

Occurs in yeast; produces alcohol and CO2 (used in bread and wine)

CAM plants

Plants adapted to hot, dry climates (succulents, cacti, orchids) that open stomata at night to conserve water

DNA structure

Double helix made of two strands of nucleotides

Base pairing rules

Adenine pairs with Thymine (A-T) and Cytosine pairs with Guanine (C-G)

Chromosomes

Structures made of tightly coiled DNA found in the nucleus

Genes

Sections of DNA that code for specific traits

DNA vs RNA

DNA is double-stranded with thymine and deoxyribose sugar; RNA is single-stranded with uracil and ribose sugar

Nucleotide

The building block of DNA and RNA, made of a sugar, phosphate, and nitrogen base

Codon

A sequence of three nucleotides that codes for one amino acid

Gene

A section of DNA that codes for a specific trait or protein

Mutation

A change in the DNA sequence

DNA replication

The process of copying DNA before a cell divides; produces two identical DNA molecules

Transcription

Process where DNA is copied to messenger RNA (mRNA) in the nucleus

Translation

Process where RNA is used to make proteins at the ribosome in the cytoplasm

Protein synthesis summary

DNA -> RNA (transcription) -> Protein (translation)

Substitution mutation

One base is swapped for another (example: A becomes G)

Insertion mutation

An extra base is added into the DNA sequence

Deletion mutation

A base is removed from the DNA sequence

Effect of mutations

Mutations can change proteins, which can change traits; can be harmful, helpful, or neutral

Genotype

The genetic makeup of an organism (the alleles; example: Bb)

Phenotype

The physical appearance or expressed trait (example: brown eyes)

Dominant trait

A trait that is expressed when at least one dominant allele is present (capital letter)

Recessive trait

A trait that is only expressed when both alleles are recessive (lowercase letter)

Homozygous

Having two of the same alleles for a trait (BB or bb); also called purebred

Heterozygous

Having two different alleles for a trait (Bb); also called hybrid

Incomplete dominance

When two alleles blend together to make a third phenotype (example: red + white = pink flower)

Codominance

When both alleles are fully expressed at the same time (example: red and white spots on a cow)

Sex-linked traits

Traits carried on the sex chromosomes (X or Y); often more common in males