ACT Science (copy)

Genetics:

• Allele: One of two or more versions of a gene. They can be dominant or recessive. Alleles

are represented by a single letter, such as b or B. Recessive alleles are represented by a

lowercase letter (i.e. b). Dominant alleles are represented by an uppercase letter (i.e. B).

• Genotype: The combination of alleles (genes) that an individual possesses for a certain

trait. Examples of genotypes: BB, Bb, bb.

• Phenotype: The physical, observable traits of an organism, such as eye color.• Recessive trait: A trait that requires two matching recessive alleles (i.e. a genotype of bb)

to be expressed. An example of a recessive trait is blue eyes.

• Dominant trait: A trait that only requires one dominant allele (i.e. a genotype of Bb) to

be expressed. An example of a dominant trait is brown eyes.

• Heterozygous: When an organism has two different alleles for a certain trait, such as Bb.

• Homozygous: When an organism has two identical alleles for a certain trait, such as BB

or bb.

• Chromatid: A strand of DNA.

• Chromosome: A cluster/segment of DNA that contains two chromatids bound together

in the form of an “X.”

• Gametes: Reproductive cells specific to each gender. For example, the human male

gamete is the sperm and the human female gamete is the egg. A gamete gets half of the

paired alleles of the parent cell’s DNA. For example, if the parent cell has genotype Bb,

then one gamete would get the dominant B allele, and another gamete would get the

recessive b allele.

• Nucleic Acids: Carriers of genetic information. DNA and RNA are both nucleic acids.

• Nucleotides: The components of Nucleic Acids. They are made up of a nitrogenous base,

a 5-carbon sugar, and a phosphate group. There are 5 basic nucleotides: adenine (A),

guanine (G), cytosine (C), thymine (T), and uracil (U).

• Purines: A class of nucleotides that includes adenine and guanine.

• Pyrimidines: A class of nucleotides that includes cytosine, thymine, and uracil.

Biology:

• Nucleus: The “brain” of a cell that contains its DNA.

• Mitochondria: The “powerhouse” of a cell that creates energy in the form of ATP.

• ATP (Adenosine Triphosphate): A molecule that stores energy that can be used by the

cell.

• Cellular respiration: The process whereby glucose (a simple sugar) and oxygen are

converted into carbon dioxide and water in order to create energy for cells. Cellular

respiration is the reverse of photosynthesis. glucose + oxygen —> carbon dioxide + water

+ energy (ATP)

• Photosynthesis: The process whereby plants convert carbon dioxide, water, and sunlight

into glucose (sugar) and oxygen. Photosynthesis is the reverse of cellular respiration.

carbon dioxide + water + energy (from the sun) —> glucose + oxygen.

• Chlorophyll is a green pigment that is used in photosynthesis.

• Glucose: A simple sugar (C6H12O6) that is produced by plants during photosynthesis and

that is broken down into energy by animals during cellular respiration.

• Osmosis: the movement or diffusion of solvent molecules through a membrane in the

direction that tends to equalize the solute concentrations on the two sides

• Aerobic: a process that requires oxygen.

• Anaerobic: A process that does not require oxygen.

• Carbohydrates: A class of compounds that includes sugars and starches. They are the

most common form of energy for animals.• Proteins: A class of compounds that are made up of amino acids. They are the building

blocks of cells.

• Lipids: A class of compounds including fats, fatty acids, oils, and hormones that are

insoluble in water. They are used to store energy, thermally insulate organisms,

communicate messages, and build components of cell membranes.

• Amino acids: The building blocks of proteins. Examples include lysine, phenylalanine,

and tryptophan.

• Hormones: Chemical messengers that regular bodily functions like hunger, mood, and

blood sugar levels. Examples include insulin, estrogen, testosterone, cortisol, oxytocin,

serotonin, and dopamine.

• Fermentation: An anaerobic process by which glucose is broken down into carbon

dioxide and either alcohol or lactic acid to create energy.

• Endotherm: A warm-blooded organism

• Ectotherm: A cold-blooded organism

• Symbiotic relationships: A relationship between species that benefits one or more of the

organisms. There are many types of symbiotic relationships, including commensalism

(one organism benefits and the other is unaffected), mutualism (both organisms

benefit), and parasitism (one organism benefits but the other is harmed).

• Taxonomic ranks: Groups that classify different organisms. The largest rank is Kingdom,

followed by Phylum, Class, Order, Family, Genus, and Species. All members of the same

species necessarily belong to the same genus, family, order, class, phylum, and kingdom.

• Decomposers: Organisms that consume decaying or dead material. Examples include

worms and mushrooms.

• Binomial nomenclature: A system of classifying and identifying living things by giving

them a name (often called the “Latin name”) that consists of two parts, the genus name

and the species name, as in Homo sapiens. The first part of the name (i.e. Homo)

represents the genus. The second part of the name (sapiens) represents the species.

Environmental Science, Earth Science, and Ecology:

• Igneous rock: formed from cooled magma and/or lava.

• Sedimentary rock: formed from the collection of small particles such as sand.

• Metamorphic rock: formed when it is subjected to forces like heat and/or pressure.

• Run-off: Process by which rainwater slides off of land and into lakes and rivers.

• Earth’s layers: Crust (outermost, thinnest layer); mantle (under the crust, the mantle is

the thickest layer and is constantly moving due to convection currents of molten rock);

outer core (under the mantle, it creates Earth’s magnetic field); inner core (innermost

layer, it is extremely hot)

• Greenhouse gases: gases such as carbon dioxide and methane that trap infrared

radiation and increase Earth’s temperature

• Autotroph: an organism that can produce its own food from sunlight, water, carbon

dioxide, and other chemicals. Plants are autotrophs.

• Heterotroph: an organism that eats other organisms. Humans are heterotrophs.

• Primary consumers: organisms (like grasshoppers) that eat autotrophs• Secondary consumers: organisms (like birds and snakes) that eat primary consumers

• Tertiary consumers: organisms (like wolves and lions) that eat secondary consumers