Key Terms in Grade 11 Biology:

Active Transport: movement of substances across cell membranes that uses energy; often moves substances against a concentration gradient.

Allele: An alternative version of a gene.

Amylase: an enzyme that breaks down complex carbohydrates.

Analogous Features: A function that performs the same function as another but not similar in in origin or anatomical structure.

Angiosperm: A plant that produces flowers.

Antioxidants: chemicals that reduce the danger of oxygen-free radicals. Vitamin C is a common antioxidant.

Anther: Floral organ that produces pollen.

Apomorphic: in cladistics, this term describes a recent characteristics that is derived from, but no longer the same as, an ancestral characteristic. Derived characteristics arose at some time after the first “splitting” of  a member from the group, and therefore derived characteristics differ among the members of the group.

Arteries: are blood vessels that carry blood away from the heart.

Asexual Reproduction: The production of offspring from a single parent; the genetic makeup of the offspring is identical to that of the parent.

Atrium: a chamber in which blood enters the heart

Basal Metabolic Rate: the minimum amount of energy that a resting animal requires to maintain life processes.

Bile: A fluid that is secreted by the liver, stored in the gallbladder, and discharged into the duodenum and aids in the digestion, and absorption of fats.

Bile Salt: a component of bile that breaks down large fat globules

Binomial Nomenclature: The formal system of naming species whereby each species is assigned a genus name followed by a specific name; the two words together form the species name.

Biodiversity: The number and variety of species and ecosystems on Earth.

Biological Classification: The systematic grouping of organisms into biological categories based on physical and evolutionary relationships.

Blood Pressure: is the pressure exerted by circulating blood upon the walls of blood vessels.

Bolus: a mass of food that has been chewed at the point of swallowing.

Capillary: a blood vessel that connects arteries and veins. Capillaries are the sites of fluid and gas exchange.

Cardiac sphincter – a valve that opens to allow food into the stomach, but also prevents stomach acid from entering the esophagus.

Carpel: Female reproductive floral part, comprising of a stigma, style, ovary, and ovule.

Cations: Ions with a positive charge.

Chemical Digestion – the process of breaking down molecules via bond cleavage(s).

Chromatin: the genetic material during Interphase.

Cirrhosis: a chronic inflammation of liver tissue characterized by an increase of non-functioning fibrous tissue and fat.

Clade: A natural group of organisms with shared derived traits.

Cladist: one who classifies organisms according to the principles of cladistics

Cladistics: A method of determining evolutionary relationships based on the presence or absence of recently evolved traits (derived traits).

Cladograms: Used to illustrate the evolutionary relationships, or phylogeny, of different groups of species of organisms.

Closed Circulatory System: the blood never leaves the network of blood vessels.  System in the human body.

Co-enzymes: Organic molecules necessary for the activity of some enzymes.

Cofactors: Substances necessary for the activity of another substance, usually an enzyme. Co-enzymes are are organic cofactors.

Colon: the largest segment of the large intestine, where water reabsorption occurs.

Coronary Circulation: Oxygen rich blood is pumped within the heart muscle.

Crop: a receptacle for storing undigested food.

Crossing Over: the exchange of genetic material between two homologous chromosomes during prophase I.

Cuticle: the waxy, water-repelling layer on the outer surface of a leaf that helps keep it from dying out (and protect it from invading bacteria, insects, and fungi)

Cytokinesis: the division of the cytoplasm.

Deamination: removal of an amino group from an organic compound, occurs primarily in the liver.

Derived Trait: see apomorphic

Detoxify: to remove the effects of a poison.

Diastole: is the period of time when the heart refills with blood after systole (contraction).

Dichotomous Key: A series of branching, two-part statements used to identify organisms or objects.

Dicotyledon: A flowering plant with two embryonic seed leaves or cotyledons that usually appear at germination.

Diploid Cells: Contains 2 copies of every chromosome (2n).

Dominant: allele determines the trait that heterozygous individual expresses.

Dormant: Describes a state of extremely slow biological activity. A dormant seed contains a living embryo but it does not grow; it remains protected by a seed coat and sometimes the fruit as well.

“Dub”: The “dub” sound occurs when the pulmonary and aortic valve open and close.

Duodenum – the first segment of the small intestine where the final majority of digestion occurs.

Electrocardiagram (ECG): is a test that measures the electrical activity of the heart.

Embryo: a zygote that has begun mitosis (cell division).

Endoscope: an instrument to view the interior of the body.

Endosperms: Nutritive tissue in an angiosperm seed.

Enterokinase: an enzyme of the small intestine that converts trypsinogen to trypsin.

žEpidermis: the protective, outler layer of cells on the surface of a leaf. The guard cells (and stoma) are part of the epidermis.

Epiglottis – a small flap of cartilage that is pushed over top of the opening to the trachea (wind-pipe), when the tongue swallows food.

Erepsins: enzymes that complete protein digestion by converting small-chain peptides to amino acids.

Esophagus: a tube that carries food from the mouth to the stomach

Eukaryote: Any organism whose cells contain organelles; some eukaryotic organisms are single celled, while others are multicellular.

Fertilization: the union of female and male sex cells.

Filament: Thin stalk that supports the anther.
Gallbladder – stores and releases bile it into the duodenum.

Gallstones: crystals of bile salts that form in the gall bladder.

Gametophyte: Produce male and female gametes (sex cells) which fuse at fertilization and develop into another sporophyte.

Gastrin: a digestive hormone secreted by the stomach that stimulates the release of gastric juices to digest proteins.

Gastrovascular Cavity: a digestive compartment, usually with a single opening that functions as both mouth and anus.

Genetic Bottleneck: A dramatic, often temporary, reduction in population size, usually resulting in significant genetic drift.

Genus: A taxonomic level consisting of a group of similar species.

Gizzard: a muscular chamber designed to physically break down food.

žGuard Cells: one of a pair of sausage-shaped cells that surround a stoma (a pore in a leaf). Guard cells change shape (as light and humidity change), causing the stoma to open and close.

Gymnosperms: A vascular plant that produces seeds in special structured called cones.

Haploid Cells: Contains half the number of chromosomes the diploid parent cell has (n)

Hardy-Weinberg Principle: In large populations in which only random chance is at work, allele frequencies are expected to remain constant from generation to generation.

Heart Valve: normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart. A heart valve opens or closes incumbent upon differential blood pressure on each side.

Homologous Chromosomes: paired chromosomes similar in shape, size, gene arrangement, and gene information.

Homologous Features: A structure with a common evolutionary origin that may serve a different functions in modern species.

Hydrolytic Enzymes: enzymes that use water to break down molecules.

Jaundice: the yellowish discoloration of the skin and other tissues brought about by the collection of bile pigments in the blood.

Kingdom: The highest taxonomic level of the traditional Linnaean system of classification.

Lacteals: small vessels that provide the products of fat digestion access to your circulatory system.

Large intestine (aka the colon) – a muscular tube that has folds but DOES NOT have villi or microvilli, and is the primary site of water absorption.

Leached: Washed away as a soluble substance by rainwater or a watering system.

Legumes: A group of angiosperms, including peas, beans, clover, and alfalfa, which tend to have nodules containing nitrogen-fixing bacteria on their roots.

Lipases: lipid-digesting enzymes.

Liver – produces a substance called bile that is stored in the gallbladder.

“Lub”: The “lub” sound is produced when the tricuspid and mitral valves open and close

Macronutrients: 9 nutrients required by plants in relatively large quantities (greater than 1000mg/kg of dry mass).

Mechanical Digestion – the breaking down of food particles into smaller particles, but DOES NOT involve breaking bonds.

Micronutrients: 8 nutrients required by plants in relatively small quantities (less than 1000mg/kg) of dry mass).

Microvilli: microscopic fingerlike outward projections of the cell membrane.

Minerals: elements (such as copper, iron, calcium, potassium, etc.) required by the body, often in trace amounts. Minerals are inorganic.

Mitosis: a type of cell division in which a daughter cell receives the same number of chromosomes as the parent cell.

Monocotyledon: Any of various flowering plants, such as grasses, orchids, and lilies, having a single cotyledon in the seed.

Mucus: a protein produced by a layer of epithelial cells known as a mucous membrane.

Natural Selection: The way in which nature favours the reproductive success of some individuals with a population over others.

Nitrogen-Fixing Bacteria: Bacteria that can convert atmospheric nitrogen gas (N2) into ammonium ions (NH4 +). They tend to live in nodules on the roots of legumes and have a symbiotic relationship with the legumes.

Nodules: Swellings on the root of legumes that contain symbiotic nitrogen-fixing bacteria.

Open Circulatory System: Blood is pumped by a heart directly into the body cavities, where tissues are surrounded by the blood.

Outgroup: in cladistics or phylogenetics, a group of organisms that serve as a reference group for determination of the evolutionary relationship among three or more monophyletic groups of organisms

žPalisade Mesophyll: a layer of elongated cells located under the upper epidermis. These cells contain most of the leaf’s chlorophyll, converting sunlight into usable chemical energy for the plant.

Pancreas – a finger-like organ that projects from the duodenum, that produces and secretes enzymes and bicarbonate ions into the duodenum.

Parsimony (principle of): in cladistics, this principle refers to the minimization of possible conflicts when constructing a cladogram

Pepsin: a protein-digesting enzyme produced by the stomach.

Peristalsis: rhythmic, wavelike contraction of smooth muscle that moves food along the gastrointestinal tract.

Pharynx: a muscular section of the digestive tract. Air and/or food passes through this muscular tube.

Phloem: The food-conducting tissue of vascular plants, consisting of sieve tubes, fibers, parenchyma, and sclereids.

Photoperiod: The number of daylight hours.

Phylogeny: The history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms.

Plasma: contains blood proteins, glucose, vitamins, minerals, dissolved gases, and waste products of cell metabolism. Proteins help maintain body homeostasis.

Platelets: are irregularly-shaped, colorless bodies that are present in blood. Their sticky surface lets them, along with other substances, form clots to stop bleeding. The mineral calcium, vitamin K, and a protein called fibrinogen help the platelets form a clot.

Plesiomorphic: in cladistics, this term describes a primitive characteristic that is thought to be ancestral to all members of the group under consideration. Primitive characteristics are widespread and cannot be used to distinguish between members of such a group.

Pollination: The transfer of pollen grains to an ovule

Primitive Trait: see plesiomorphic

Prokaryote: A single-celled organism that does not contain membrane-bound organelles.

Pulmonary Circulation: Oxygen poor blood is pumped into the lungs; oxygen rich blood is carried back to the heart.

Recessive: allele is not expressed in heterozygous individual.

Red Blood Cells: Deliver oxygen to the body tissues received from lungs and remove carbon dioxide from the bodies tissues

Root System: A developed system of roots.

SA Node: the nerve impulse that controls the normal rhythm of the heart; the natural pacemaker of the heart.

Secretin: a hormone that stimulates pancreatic and bile secretions.

Seed: Reproductive structure of plants made up of an embryo, stored food, and a tough waterproof coat.

Sexual Reproduction: The production of offspring from the fusion of two sex cells (2 parents); the genetic makeup of the offspring is different from that of either parent.

Shoot System: The aerial portion of a plant, including stem, branches, and leaves.

Small intestine – A long tubular organ where the majority of digestion and absorption occur. The lining of the small intestine is folded and is lined with villi on which there are more, smaller projections called microvilli.

Speciation: The formation of new species.

Species: All organisms capable of breeding freely with each other under natural conditionS.

Sphygmomanometer: is devise used to measure blood pressure.

žSpongy Mesophyll: irregularly-shaped cells with many air spaces between the cells. These cells contain some chlorophyll. The spongy mesophyll cells communicate with the guard cells (stomata), causing them to open or close, depending on the concentration of gases.

Sporophyte: A diploid organism that produces haploid spores which can develop without fertilization.

Stamen: Male reproduction floral part, comprising of the anther and filament.
Stomach – a muscular j-shaped organ in which food is both chemically and mechanically digested.
žStoma: a pore (or opening) in a plant’s leaves where water vapor and other gases leave and enter the plant. Stomata are formed by two guard cells that regulate the opening and closing of the pore.
Stigma: Sticky surface on top of the style.
Style: Stalk that lead to the ovary
Synapomorphy: A derived trait shared by two or more species or groups.

Synapsis: the pairing of homologous chromosomes.

Systemic Circulation: Oxygen rich blood is carried to body tissues; oxygen poor blood is carried back to the heart.

Systole: a force that drives blood out of the heart. Without qualifiers, it usually means the contraction of the left ventricle.

Taxonomy: The science of classifying all organisms; taxonomists classify both living and fossil species.

Taxon:  category used to classify organisms.

Tetrad: a pair of homologous chromosomes each with two chromatids.

Trypsin: a protein-digesting enzyme

Ulcer: a lesion along the surface of an organ.

Vascular Bundle: A strand of primary tissues found within the stem of a plant and consisting of xylem and phloem, along with cambium.

Veins: are blood vessels that carry blood towards the heart.

Villi: small fingerlike projections that extend into the small intestine which increase surface area for absorption.

Ventricles: is one of two large chambers that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs.

Vitamins: organic molecules needed in trace amounts for normal growth and metabolic processes.

White Blood Cells: Also called Leukocytes; Protect the body from disease; Will produce antibodies in the body to fight off germs and infection

Xylem: The supporting and water-conducting tissue of vascular plants, consisting primarily of tracheids and vessels; woody tissue.

Zygote: a cell resulting from the union of a male and female sex cell.


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