AP Bio: Topics 1-3

Basal metabolic rate: The minimum amount of energy the body uses while at rest to keep basic life processes working.

Scaling relationships: Relationships between an organism’s body size and characteristics such as its metabolic rate.

Interstitial fluid: Fluid that surrounds and bathes the cells of the body.

Internal environment: The conditions surrounding an organism’s cells.

External environment: Everything outside of an organism that can affect it.

Regulation: The process of controlling internal conditions so they stay within a suitable range.

Conformity: When an organism’s internal conditions change as the external environment changes.

Thermoregulation: The regulation of body temperature so it stays within a suitable range.

Homeotherm: An organism that maintains a relatively constant body temperature even when the outside temperature changes.

Thermoneutral zone: The range of environmental temperatures where an animal does not need to use extra energy to maintain its body temperature.

Poikilotherm / Ectotherm: An organism whose body temperature changes with the environment and that relies mainly on external sources of heat.

Nonshivering thermogenesis: Producing heat without shivering by increasing metabolic activity.

Brown adipose tissue (BAT): Specialized fat tissue that produces heat by using stored energy.

Hibernation: A state of greatly reduced metabolism, body temperature, and activity that helps an animal survive cold conditions or a lack of food.

Homeostasis: The maintenance of relatively stable internal conditions despite changes in the internal or external environment.

Sensors / Receptors: Structures that detect changes in the internal or external environment.

Control centers / Control mechanisms: Structures that receive information from sensors and determine what response is needed.

Effectors: Structures, such as muscles or glands, that carry out the response.

Feedback: Information about a response that is used to control or adjust a process.

Negative feedback: A response that reverses or reduces the original change and helps maintain homeostasis.

Positive feedback: A response that increases or strengthens the original change.

Root: A plant organ that anchors the plant and absorbs water and minerals from the soil.

Shoot: The aboveground part of a plant, including stems, leaves, and buds.

Stem: Supports the plant and transports water, minerals, and sugars.

Leaves: Plant organs that carry out most photosynthesis and gas exchange.

Bud: An undeveloped shoot that can grow into leaves, stems, or flowers.

Lateral meristem: Tissue that produces secondary growth, making a plant wider or thicker.

Apical meristem: Tissue at the tips of roots and shoots that produces primary growth, making the plant longer.

Cell wall: A rigid structure outside the cell membrane that supports and protects plant cells.

Cellulose: A carbohydrate that makes up much of the plant cell wall and gives it strength.

Totipotency: The ability of a plant cell to develop into an entire plant.

Cotyledon: A seed leaf that provides nutrients to a developing plant embryo.

Shoot apical meristem: The meristem at the tip of a shoot that produces new stems and leaves.

Root apical meristem: The meristem at the tip of a root that produces new root cells and allows the root to grow longer.

Epidermis: The outer layer of cells that covers and protects a plant.

Cuticle: A waxy layer on the epidermis that helps prevent water loss.

Ground tissue: Plant tissue that performs functions such as photosynthesis, storage, and support.

Parenchyma: Living, relatively unspecialized cells that perform functions such as photosynthesis and storage.

Collenchyma: Living cells with unevenly thickened walls that provide flexible support.

Sclerenchyma: Cells with thick, rigid walls that provide strong support.

Xylem: Vascular tissue that transports water and minerals, mainly from the roots upward.

Vessel elements: Specialized xylem cells that form tubes for transporting water.

Phloem: Vascular tissue that transports sugars and other organic nutrients throughout the plant.

Sieve tube elements: Specialized phloem cells that form tubes for transporting sugars.

Companion cells: Cells that support and help sieve tube elements transport sugars.

Determinate growth: Growth that stops after a structure reaches a certain size.

Indeterminate growth: Growth that continues throughout a plant’s life.

Primary growth: Growth that increases the length of roots and shoots.

Secondary growth: Growth that increases the width or thickness of roots and stems.

Root cap: A structure that protects the root apical meristem as the root grows through soil.

Zone of cell elongation: The region of the root where newly produced cells grow longer, causing the root to extend.

Zone of cell maturation: The region where root cells finish developing and become specialized.

Taproot systems: Root systems with one large main root and smaller lateral roots.

Fibrous root systems: Root systems made up of many thin roots of similar size.

Vascular bundles: Groups of xylem and phloem that transport materials through a plant.

Blade: The broad, flat part of a leaf that captures light for photosynthesis.

Mesophyll: The internal leaf tissue where most photosynthesis occurs.

Petiole: The stalk that connects the leaf blade to the stem

Calorie: A unit of energy; the amount of energy needed to raise the temperature of 1 gram of water by 1°C.

Kilocalorie: 1,000 calories; the unit commonly used to measure energy in food.

Joule: The standard scientific unit used to measure energy.

Essential nutrient: A nutrient that the body needs but cannot make in sufficient amounts, so it must come from the diet.

Standard amino acids: The 20 amino acids commonly used to build proteins.

Essential amino acids: Amino acids that the body cannot make and must obtain from food.

Essential fatty acids: Fatty acids that the body cannot make and must obtain from food.

Vitamin: An organic nutrient needed in small amounts for normal body functions.

Mineral: An inorganic nutrient needed by the body for normal functions.

Malnutrition: Poor nutrition caused by getting too little, too much, or an unbalanced amount of nutrients.

Deficiency disease: A disease or health problem caused by not getting enough of a particular nutrient.

Metabolic rate: The rate at which an organism uses energy.

Macromolecule: A large biological molecule, such as a protein, carbohydrate, lipid, or nucleic acid.

Polymer: A large molecule made of many smaller repeating units called monomers.

Monomer: A small molecule that can join with other monomers to form a polymer.

Lipids: A group of mostly water-insoluble molecules that includes fats, oils, phospholipids, and steroids.

Triglycerides: Lipids made of one glycerol molecule attached to three fatty acids; they are an important form of stored energy.

Saturated: A fatty acid containing only single bonds between its carbon atoms.

Unsaturated: A fatty acid containing one or more double bonds between its carbon atoms.

Phospholipids: Lipids made of glycerol, fatty acids, and a phosphate-containing group; they are major components of cell membranes.

Phospholipid bilayer: Two layers of phospholipids that form the basic structure of cell membranes, with hydrophilic heads facing water and hydrophobic tails facing inward.

Carbohydrate: A molecule made mainly of carbon, hydrogen, and oxygen that is used for energy, energy storage, and structure.

Monosaccharides: Single sugar molecules that are the simplest carbohydrates and the building blocks of larger carbohydrates.

Polysaccharides: Large carbohydrates made of many monosaccharides joined together.

Starch: A polysaccharide used by plants to store energy.

Glycogen: A polysaccharide used by animals to store glucose.

Cellulose: A structural polysaccharide that makes up much of the plant cell wall.

Nucleic acids: Macromolecules that store and transmit genetic information; DNA and RNA are nucleic acids.

Nucleotide: The monomer that makes up nucleic acids; it contains a sugar, phosphate group, and nitrogenous base.

Base: The nitrogen-containing part of a nucleotide that helps carry genetic information.

DNA: A nucleic acid that stores an organism’s genetic information.

DNA structure: DNA consists of two nucleotide strands twisted into a double helix. The sugar-phosphate backbones are on the outside, while the bases pair on the inside.

Pyrimidines: Smaller nitrogenous bases with one ring: cytosine (C) and thymine (T) in DNA.

Purines: Larger nitrogenous bases with two rings: adenine (A) and guanine (G).

Four bases of DNA: Adenine (A), thymine (T), cytosine (C), and guanine (G).

5′ to 3′ orientation: DNA strands have direction. One strand runs 5′ → 3′ and the opposite strand runs 3′ → 5′.

RNA: A nucleic acid that helps use genetic information to make proteins.

RNA structure: RNA is usually a single strand of nucleotides containing ribose sugar, phosphate groups, and nitrogenous bases.

Four bases of RNA: Adenine (A), uracil (U), cytosine (C), and guanine (G).