SL Biology All Definitions

10 Percent Rule

The rule that only 10% of energy is passed from one trophic level to the next while the other 90% of energy is lost between trophic levels.

70s Ribosomes

Ribosomes that are smaller in size and freer in cytoplasm, used for protein synthesis.

80s Ribosomes

Larger ribosomes in eukaryotic cells that are made up of a smaller 30s subunit and a larger 50s subunit and are often associated with different cell organelles.

A Vertical Line With Two Diagonal Lines (Pedigree)

Represents identical twins.

A-Band

The strand that appears dark in the cardiac muscle and the length remains unchanged during muscle contraction.

Abiotic

The nonliving things within an ecosystem.

Absorption

The moving of food into the cells.

Absorption Spectrum

A graph showing the percentage of light absorbed at each wavelength by a pigment.

Acetylcholine

The neurotransmitter that causes muscle contraction; is made up of acetic acid and choline synthesized.

Acetylcholinesterase

This enzyme does not break down neonicotinoids so the binding is irreversible, preventing synthetic transmission resulting in losses and death. Neonicotinoids. Acetylcholinesterase.

Acid Reflux

The backward flow of stomach acid into the esophagus and can cause heartburn.

Action Spectrum

A graph showing the rate of photosynthesis at each wavelength of light.

Active Site

A region on the surface of an enzyme to which substrates bind and which catalyzes the reaction.

Active Transport

A process that allows the cell to take in substances even though there is a higher concentration in the cell; molecules enter a protein pump, and ATP is used.

Adaption

The ability of a species to be able to respond to environmental changes, such as the peppered moth tending to have a darker colouration in areas where sulfur dioxide killed lichen from trees.

Adhesion

Particles of different substances sticking together; in the case of water, it occurs as a result of the polarity of a water molecule and its ability to form hydrogen bonds.

Adult Stem Cells

The daughter cell of an embryonic stem cell, they have limited functions, and are multipotent.

Advantageous Variations

These variations ensure that individuals that can best compete for resources will survive long enough to reproduce and pass on the trait.

Advantages of Immobilized Enzymes

They can easily separate from the product, retrieved enzymes can be reused, increases stability, and can be exposed to higher enzyme concentrations.

Aerobic Cellular Respiration

Glucose is broken down in the presence of oxygen to produce ATP, and one glucose molecule yields a maximum of 38 ATP.

Albumin

Binds to bilirubin to allow for excretion.

Allele

Various forms of a gene that occupy the same locus of the chromosome but have different variations.

Alpha Cells (Insulin)

They synthesize and secrete glucagon if the blood glucose level falls below the set point.

Alveoli

Tiny air sacs made from epithelial tissue and are surrounded by blood vessels called capillaries; gas exchange takes place here.

Amber

A preserved tree resin that preserves organic material that other fossils do't, insects and plants are most often captured.

Amino Acids

Carbon atom bonds to 4 different things: amine group, carboxyl group, a hydrogen atom, an R group which is just represented by an R; there are 20 main ones.

Amniocentesis

A needle is used to withdraw a sample of amniotic fluid containing fetal cells from the amniotic sac, taken after the 14th week and has a miscarriage risk of 1%.

Amphibia

Have moist skin and use the skin for respiratory exchange, largely terrestrial animals that breed in water, fertilization is external, larval stage is aquatic, undergoes metamorphosis to become an adult, are cold-blooded; includes frogs and toads.

Amphipathic

Substances that are both attracted and not attracted to water.

Amylase

Digests starch.

Amylopectin

A form of branched starch.

Amylose

A form of unbranched starch.

Anabolism

Reactions that create larger molecules from smaller ones, require energy supplied in the form of ATP.

Anaerobic Cellular Respiration

Glucose can be broken down without using oxygen to yield a small quantity of ATP which is useful when a rapid burst of ATP production is needed, when oxygen supplies run out in respiring cells, and in environments that are deficient in oxygen.

Analogous Structures

Features of different species that are similar in function, but not necessarily in structure, so they are not derived from a common ancestor.

Analyse (Command Terms)

Break down in order to bring out the essential elements or structure.

Anaphase (Mitosis)

The stage in mitosis where the sister chromatids split into individual chromosomes, and each chromosome is pulled to an opposite pole by the centriole.

Anaphase I (Meiosis)

Spindle fibres contract and separate homologous chromosomes, sister chromatids remain attached at the centromere, each pole has a haploid set of chromosomes.

Anaphase II (Meiosis)

Spindle fibres contract and sister chromatids separate, sister chromatids move to opposite poles of the cell.

Anatomy

The science that studies the structure of the body.

Angiospermophyta

Many are herbaceous (non-woody) while others are trees or shrubs, have vascular tissue for conducting water and nutrients around the plant, leaves are elaborate structures with a waxy and waterproof covering and pores on the surface, flowers are unique to this phylum, and seeds inclosed into a fruit; includes lilies and peach trees.

Anions

Ions with a negative net charge.

Annelids

Worm-like animals with a soft body, built with a fixed number of similar segments which contain the same pattern of nerves, blood vessels, and excretory organs, sense organs and feeding structures are found at the anterior end (cephalization), ventral nerve cord runs the length of the body; includes earthworms.

Annotate (Command Terms)

Add brief notes to a diagram or graph.

Anorexia

It is a complex psychiatric illness caused by voluntary starvation and loss of body mass; signs can include hair falling out, dry skin, rusing, and loss of period.

Antagonistic Muscles

A muscle that opposes the action of another which happens as muscles can only be in two states: contracting and relaxing.

Anthropogenic Activities

Change caused by humans.

Antibiotic Resistance

When bacteria becomes resistant to antibiotics and can be avoided if antibiotics is prescribed for only serious infections, hygiene is prevented and companies develop new types of antibiotics.

Antibiotics

Chemotherapeutic agents that inhibit or prevent bacterial growth and they do no work on viruses.

Antibody

A protein (immunoglobulin) that responds to infectious agents by attaching to specific pathogen antigens; the tip of antibodies become specialized for specific antigens.

Anticodon

A trinucleotide sequence located at one end of a tRNA molecule; is the corresponding codon in a mRNA sequence.

Antigen

A specific molecule or structure on a foreign material that can bind to an antibody.

Antiperistalsis

Also known as vomiting and involves the skeletal muscles of the abdomen.

Antisense Strand

The non-coding DNA strand of a gene; acts as the template and has a complementary sequence to both the RNA and the sense strand.

Anus

The place where stool is excreted from the body.

Aorta

The body's largest artery, which carries oxygenated blood to the head and body; it is connected to the left ventricle, and all smaller branches stem from the aorta.

AP Students

They wish they were IB students.

Apex

The base of the heart where the contraction of the ventricle begins.

Apical Surface

The surface of the villi facing the lumen.

Aplysia

This is a large sea snail that is often used in research because it has very few, but very large neurons that can be seen easily open as a defense mechanism and can learn from experience.

Apoptosis

A natural part of the cell cycle where cells that are no longer useful undergo cell suicide.

Aqueous Solution

Water is the solvent in this type of solution.

Archaea

Extremophile bacteria with DNA in a circular genome, histones present, usually no introns in genes, cell walls not made of peptidoglycan, and membranes that differ from those of eubacteria and eukaryotes.

Arteries

Large, thick, muscular blood vessels composed of three layers that carry blood away from the heart and towards the rest of the body.

Arterioles

A smaller branch of an artery that stems from the aorta.

Arteriosclerosis

The development of fatty tissue called atheroma is usually caused by high blood pressure, glucose levels or consumption of trans fats and can lead to angina, stroke, kidney disease, or aortic aneurysm.

Arthropoda

Can be divided into crustaceans, arachnids, centipedes, millipedes, and insects; have segmented bodies covered by an exoskeleton made of chitin, body function coordinated by a ventral nerve cord; largest phylum in the animal kingdom.

Artificial Classification

This type of classification uses arbitrary characteristics to group organisms together and does not actually show evolutionary links; this includes classifying by things such as alphabetical order or endangeredness.

Artificial Insemination

When sperm collected from sperm banks is inserted into a woman's cervix by a doctor.

Artificial Pacemaker

A small, battery-operated device that senses when the heart is beating irregularly.

Aseptic Technique

Following strict rules, measures, and practices to avoid contamination from pathogens.

Asexual Reproduction

When an organism reproduces by making a copy of itself. Offspring are clones and there is not much genetic variation.

Assimilation

The process of making food part of the cell.

Atmosphere

The sphere composed of all of the Earth's gases.

Atrioventricular Node (AV)

Passes the nerve impulses to the ventricles causing them to contract; signal from SA to AV is delayed for about 0.12s which allows atria to contract and empty the blood they contain before the ventricles contract.

Autonomic Nervous System

Regulates of visceral functions over which there is generally no conscious control such as heart rate got peristalsis Etc.

Autonomic Nervous System (ANS)

System that controls body processes that are not under our conscious control including the digestive system by using hormones released by glands in the body

Autoradiography

An imaging technique that uses radioactive sources contained within the exposed sample.

Autosomal Dominant Pattern of Inheritance (Pedigree)

Occurs when the disease -causing allele is dominant; usually every generation has an affected individual and unaffected parents cannot have an affected child.

Autosomal Recessive Pattern of Inheritance (Pedigree)

Occurs when the disease-causing allele is recessive and two unaffected parents can have an affected child if they are carriers; can skip generations.

Autosomes

Chromosomes that do not determine sex and occur in "matching" homologous pairs.

Autotroph

They can use photosynthesis or chemosynthesis to fix carbon into organic compounds and are commonly known as producers

Aves

Have a strong, light skeleton, limb and hollow bones, feathers, forelimbs modified as wings, are endothermic, and have internal fertilization but eggs are laid; are birds.

Axons

Parts of neuron that convey messages rapidly in an electrical form called a nerve impulse.

Basal Surface

The surface of the villi facing the blood vessels.

Behavioural Isolation

Isolation through species developing different behaviours.

Beneficial Mutations

Mutations that help the survival or an organism.

Benefits of Genetically Modified Organisms (GMOs)

Can add nutritional value to foods, can be produced with lack of known allergens, has better yield as it can be grown in harsher conditions, can produce herbicide, can improve food supply, has longer shelf lives, and reduces economic costs and carbon footprint.

Beta Cells (Insulin)

They synthesize insulin and secrete it when the blood glucose concentration rises above the set point.

Bicuspid Valve

Controls the flow of blood from the left ventricle to the aorta.

Bilayer

Composed of two molecules in which each molecule is arranged with its hydrophobic end directed inward toward the opposite side of the film and its hydrophilic end directed outward.

Binary Fission

A form of asexual reproduction where the parent cell divides into two genetically identical daughter cells.

Binomial System

A naming system used by scientist to identify a species and show and better show evolutionary links between species; the first name is the genus name and is capitalized, while the second name is the species name which starts with a lowercase letter; it is italicized in typed text and underlined in written text.

Biosphere

The sphere composed of all life on Earth.

Biotic

The living things within an ecosystem.

Blood Clotting

The process in which platelets form at the site of a cut and form a temporary plug, releasing clotting factors; this is usually good as it can heal wounds however blood clot in the coronary are bad as they cut off blood supply to the heart.

Blood Glucose

This is maintained through the action of the pancreas and the liver, it is a negative feedback loop.

Blood Plasma

The pale yellow liquid component of blood that make up 55% of the body's total blood volume; they are up to 95% water and 6-8% dissolved proteins.

Blood Pressure

The measure of the force of blood against the blood vessels; arterial blood tends to have the most pressure followed by the capillaries then the veins; has two values, the systolic pressure (larger number), and the diastolic pressure (smaller number).

Blood Valves

Small crescent-shaped flaps of tissue that help prevent a backflow of blood.