Science Biology and Physics Revision Flashcards

These flashcards cover fundamental concepts from Biology (genetics, DNA structure, mitosis, meiosis, and evolution) and Physics (motion laws, scalars/vectors, and energy forms) as described in the revision notes.

DNA

deoxyribonucleic acid, the chemical compound, carries inherited information in cell and protein production

Nucleotide

structural unit of DNA, made of sugar, phosphate, and a nitrogen base

Gene

a section of DNA, codes for a particular trait

Chromatin

highly coiled DNA molecule

Chromosome

super coiled chromatin, forms a rod-like structure, contains genes of an individual

DNA replication

a DNA molecule forms an EXACT COPY of itself

Protein

controls chemical reactions in the body, made of amino acids

Helicase

enzyme responsible for separating the 2 sides of the DNA molecule

DNA polymerase

enzyme responsible for attaching loose nucleotides to DNA strand

Ligase

enzyme responsible for repairing the bonds that hold the backbone of the nucleotide together

Allele

an alternative form of gene, occurs at a given point in a chromosome

Dominant

where one allele masks the effect of another allele

Recessive

the allele shown if it is not masked by the dominant allele

Genotype

the genes present in an individual, represented by letters (eg. Rr, RR, rr)

Phenotype

the physical appearance of an individual, determined by the genotypes

Homozygous

2 identical alles for a given gene (eg. AA, aa)

Heterozygous

2 different alleles for a given gene (eg. Aa)

punnett square

a table used to calculate genetics problems

Autosomal

the 22 pairs of chromosomes that are NOT sex chromosomes

sex-linked

a trait controlled by a gene found on a sex chromosome (usually the X chromosome)

Pedigree

a diagram showing how a trait is passed through a family

Nitrogen bases

adenine, thymine, guanine, and cytosine, where A only pairs with T and C only pairs with G

Complementary base pairing

the concept that the four nitrogen bases can only pair up one way due to their chemical structures

Double helix

twisted ladder shape of DNA with sides of alternating sugar and phosphate molecules and 'rungs' made of base pairs

cell cycle

the series of stages a cell goes through as it grows and divides

Mitosis

the process where one cell divides to make two identical cells

Diploid (2n)

a cell with the full set of chromosomes

Haploid (n)

a cell with half the number of chromosomes

Sister chromatids

the two identical copies of a chromosome joined in the middle

Centromere

the point where sister chromatids are attached

Cytokinesis

the cell splits into two identical daughter cells

Gametes

sex cells (sperm and egg)

Prophase

Chromosomes become visible and the nucleus starts to break down

Metaphase

Chromosomes line up in the middle of the cell

Anaphase

Sister chromatids are pulled apart to opposite sides of the cell

Telophase

new nuclei form around each set of chromosomes

Meiosis

produces four genetically different haploid cells for sexual reproduction by halving the chromosome number

Trait

an inherited feature of an organism (also called a characteristic)

Evolution

the gradual change in the characteristics of a species over a period of time

Natural selection

the process by which a species becomes better adapted to its environment

Mutation

a new variation, caused by the permanent change in a gene or chromosome

Allopatric speciation

speciation caused by geographical separation

Sympatric speciation

Speciation without geographical separation

Scalars

quantities that have magnitude only, such as distance, speed and mass

Vectors

quantities that have both magnitude and direction, such as displacement, velocity and force

Displacement

the straight-line change in position from start to finish including direction

Newton's First Law

An object will remain at rest or continue moving at constant velocity unless acted upon by an unbalanced force; also called the law of inertia

Newton's Second Law

states that force equals mass multiplied by acceleration, written as $F=ma$

Newton's Third Law

For every action force, there is an equal and opposite reaction force

Kinetic energy

the energy an object has because it is moving; increases with mass and speed

Elastic potential energy

stored when an object is stretched, compressed or bent and can return to its original shape

Gravitational potential energy

stored due to an object's position above the ground; depends on mass and height

Chemical potential energy

stored in the bonds between atoms and molecules

Nuclear potential energy

stored within the nucleus of atoms, released during fission or fusion

Sankey diagrams

diagrams showing how energy is transferred where the width represents energy amount, vertical arrows represent useful energy, and downward arrows represent wasted energy

Efficiency

measures how much input energy is converted into useful output energy, calculated as $\text{Efficiency} = \frac{\text{Total Energy Input}}{\text{Useful Energy Output}} \times 100$