Exam 1 Review for People and the Living Environment

Homeostasis

The ability to maintain a constant, tolerable internal environment despite changes in the external environment.

Ecosystem

A biological community together with its physical habitat.

Photosynthesis

The process by which some organisms convert solar energy into the chemical energy of nutrient molecules.

DNA

The long molecule that encodes the information specifying what a cell or organism will be like.

Molecules

Atoms can be joined together to form these at the cellular level of biological organization.

Genes

Only certain of these are active or expressed within certain types of cells, leading to differences in cells.

Kingdoms

The diversity of life-forms is sorted into 5 of these.

Atomic number

Atoms with the same this are said to belong to the same element.

Electrons

Sulfur has an atomic mass of 32 and an atomic number of 16; thus, the total number of these for this element is 16.

Isotopes

Different atoms that have the same number of protons but different numbers of neutrons.

Polar molecule

The unequal sharing of electrons between the oxygen and hydrogen atoms within a water molecule makes water this type of molecule.

pH

As the hydrogen ion concentration of a solution decreases, this increases.

Potential energy

Electrons carry more of this the farther they are from the nucleus, and this energy is used to drive chemical reactions.

Hydrogen bond

The bond formed between the hydrogen atom of one water molecule and the oxygen atom of another water molecule.

Hydrophobic

Water tends to shy away from nonpolar, or this type of molecule, which is thus not soluble in water.

Monosaccharides

Carbohydrates are composed of one or more monomers called these.

Hydrolysis

Breaking the bonds between the subunits of a polymer involves this type of reaction.

Hydrophobic portions

In the stable form of protein, these are generally oriented to the interior of the protein molecule.

Saturated fatty acids

These have only single bonds between their carbon atoms within the chains and make fats solid at room temperature.

Keratin

The structural protein that forms hair, nails, and feathers.

Polypeptide folding

Contributes to the way a polypeptide folds into a functional protein.

Monomers

Linked together to form fat molecules, or lipids.

Excess glucose storage

Animals store excess glucose in the form of glycogen.

Phospholipid head

Contains a phosphate group and is very polar.

Phospholipid bilayer

When mixed with water, phospholipid molecules can spontaneously organize into a bilayer with the 'tails' located in the center.

Exocytosis

A type of bulk transport where molecules move out of a cell via secretory vesicles.

Lysosomes

Vesicles that are surrounded by a membrane and that arise from the Golgi apparatus.

Diffusion

Defined as the net movement of molecules from areas of higher concentration to areas of lower concentration.

Cells

The smallest living things, the basic units of organization of all organisms.

Ribosome assembly

Ribosomes are assembled in the nucleolus.

Prokaryotic cells

Do not have a nucleus because they do not contain DNA.

Energy conversion

All forms of energy can be converted into heat.

Endergonic reaction

A reaction in which the products contain more energy than the reactants.

Competitive inhibition

Inhibition where a signal molecule interferes with the active site of an enzyme.

ATP

An energy molecule composed of a nitrogen-containing base called adenine.

Feedback inhibition

Occurs when an end product binds to an enzyme's active site, which prohibits substrate binding and inactivates the metabolic pathway.

Enzymes

Have no effects on the energy levels of the reactants or products of reactions, only the energy of activation.

Work

The ability to do work.

Essential nutrients

Must be synthesized within the body—they cannot be obtained through food intake.

Absorption

During digestion, smaller food molecules pass across the lining of the digestive gut and back into the body fluids.

HCl production

Produced by parietal cells in the stomach.

Enzyme for fat breakdown

An enzyme that breaks down fat droplets into monoglycerides and free fatty acids.

Lipase

An enzyme that breaks down fat droplets into monoglycerides and free fatty acids.

Gallbladder

A pear-shaped, muscular sac where bile is stored.

Amylase

Pancreatic enzyme that helps to break down carbohydrates into glucose.

Excretion

The process during which undigested waste products are expelled from the body.

True

Gravity is necessary to move food down the esophagus and toward the stomach.

Motor neurons

Also known as efferent neurons, this cell type carries impulses from the CNS to muscles and glands.

Cones

Photoreceptors that allow color vision.

Semicircular canals

Structures of the inner ear involved in detecting motion of the body.

Retina

The sheetlike layer of photoreceptors at the back of the eye.

Cerebellum

The part of the brain that controls balance, posture, and muscular coordination.

Involuntary nervous system

The nervous system that controls reflexes.

Interoceptors

A variety of sensors the body uses to respond to different aspects of its internal environment.

Integration

The process where synaptic signals interact with one another in the body of a neuron.

Eukaryotic cells

Cells that contain membrane-bound organelles.

Prokaryotic cells

Cells that lack membrane-bound organelles found in eukaryotes.

Endosymbiotic theory

The theory that some organelles evolved through a symbiotic relationship between eukaryotic and prokaryotic cells.

Intracellular digestion

A process where some organisms digest food within their cells.

Extracellular digestion

A process where some organisms digest food outside their cells.

Plasma membrane

The structure that allows materials to be transported into and out of the cell.

Natural selection

The theory proposed by Charles Darwin explaining how species evolve over time.