Science Exam Biological & Physics Flashcards

Learn the two decks seperately first.

Define Scalar Quantity

A quantity that has magnitude (size) only. | Working/Explanation: Scalar quantities, such as mass, time, and temperature, are described by a numerical value and a unit but do not possess a direction [1], [2].

Define Vector Quantity

A quantity that has both magnitude (size) and direction. | Working/Explanation: Vector quantities, such as velocity, displacement, and force, require both a numerical size and a specific direction to be fully described [1], [3].

S.I. Unit for Distance

Meter (m) | Working/Explanation: The standard unit of length or distance in the International System of Units is the meter [4], [5].

S.I. Unit for Mass

Kilogram (kg) | Working/Explanation: The standard unit for measuring the amount of material an object is made of is the kilogram [4], [6], [5].

S.I. Unit for Time

Second (s) | Working/Explanation: The standard unit for time in scientific calculations is the second [4], [5].

S.I. Unit for Force

Newton (N) | Working/Explanation: Force is measured in Newtons, representing a push or pull acting upon an object [4], [6], [5].

S.I. Unit for Energy

Joule (J) | Working/Explanation: The Joule is the standard unit used to record energy or work done [4], [7], [5].

Conversion: km/h to m/s

Divide by 3.6 | Working/Explanation: To convert from kilometers per hour to the S.I. unit of meters per second, you must divide the value by 3.6 [8], [9].

Conversion: m/s to km/h

Multiply by 3.6 | Working/Explanation: To convert from meters per second to kilometers per hour, you multiply the value by 3.6 [8], [9].

Conversion: Grams to Kilograms

Divide by 1000 | Working/Explanation: Since there are 1000 grams in a kilogram, you divide the mass in grams by 1000 to get the value in kg [10], [11].

Define Distance

The total length of the path an object has travelled. | Working/Explanation: Distance is a scalar quantity measured in meters, representing the entire journey regardless of direction [12], [13].

Define Displacement

The straight-line distance between the starting and finishing points. | Working/Explanation: Displacement is a vector quantity measured in meters that includes the direction from start to finish [12], [13].

Define Speed

The rate at which an object covers distance. | Working/Explanation: Speed is a scalar quantity calculated as distance divided by time (v = d/t) [14], [13].

Define Velocity

The rate of change of displacement. | Working/Explanation: Velocity is a vector quantity (speed in a given direction) calculated as displacement divided by time (v = s/t) [15], [14], [13].

Acceleration Formula

a = (v - u) / t | Working/Explanation: Acceleration (m/s²) equals the final velocity (v) minus the initial velocity (u), all divided by the time taken (t) [16], [17].

Define Acceleration

The rate of change of velocity. | Working/Explanation: Acceleration is a vector quantity that describes how much an object's velocity changes every second [18], [16], [19].

Newton's First Law (Law of Inertia)

An object will remain at rest or move at a constant velocity unless acted upon by an unbalanced force. | Working/Explanation: Inertia is the property of an object to resist changes in its state of motion [20], [21], [22].

Newton's Second Law Formula

F = ma | Working/Explanation: The net force (N) acting on an object is equal to its mass (kg) multiplied by its acceleration (m/s²) [20], [23], [22].

Newton's Third Law

For every action, there is an equal and opposite reaction. | Working/Explanation: Forces always occur in pairs; if object A exerts a force on object B, object B exerts an equal force back on object A in the opposite direction [20], [24], [19].

Energy Transfer

The flow of energy from one object to another where the type of energy does not change. | Working/Explanation: For example, heat moving from a stove to a pot of water is a transfer of thermal energy [25], [26].

Energy Transformation

The conversion of one form of energy into another form of energy. | Working/Explanation: For example, a battery transforms chemical energy into electrical energy [25], [26].

Law of Conservation of Energy

Energy can neither be created nor destroyed, only transferred or transformed. | Working/Explanation: The total amount of energy in a closed system remains constant [27], [28].

Energy Efficiency Formula

(Useful Energy Output / Total Energy Input) x 100 | Working/Explanation: This calculates the percentage of input energy that is converted into the desired useful form [29], [30].

Sankey Diagram: Arrow Width

Represents the quantity (amount) of energy. | Working/Explanation: In a Sankey diagram, a wider arrow indicates more energy flowing through that part of the system [25], [31].

Sankey Diagram: Arrow Direction

Straight arrows represent useful energy; bent/downward arrows represent wasted energy. | Working/Explanation: Useful energy output usually goes to the right, while wasted energy (like heat or sound) is shown branching off [29], [31].

DNA Stand For

Deoxyribonucleic acid | Working/Explanation: DNA is the chemical compound that carries inherited information and codes for protein production [32], [33].

Watson-Crick Model

The double helix structure of DNA. | Working/Explanation: First successfully described in 1953, this model depicts DNA as a twisted rope ladder [34], [35].

Structural Unit of DNA

Nucleotide | Working/Explanation: DNA is a polymer made of repeating subunits called nucleotides [36], [34], [33].

Three Components of a Nucleotide

Phosphate group, deoxyribose sugar, and a nitrogenous base. | Working/Explanation: These three molecules bond together to form the basic building block of DNA [36], [33].

The Four Nitrogenous Bases

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). | Working/Explanation: These bases form the "rungs" of the DNA ladder and carry the genetic code [32], [36], [33].

Complementary Base Pairing Rule

Adenine pairs with Thymine (A-T); Cytosine pairs with Guanine (C-G). | Working/Explanation: Bases bond specifically due to their chemical shapes; A-T are held by 2 hydrogen bonds, C-G by 3 [36], [37], [38].

Role of Helicase

Unzips the DNA double helix. | Working/Explanation: This enzyme breaks the hydrogen bonds between the nitrogenous bases to expose the template strands [39], [40], [41].

Role of DNA Polymerase

Adds free nucleotides to the exposed bases. | Working/Explanation: This enzyme follows base-pairing rules to build a new complementary strand of DNA [39], [42], [41].

Role of DNA Ligase

Seals the gaps in the sugar-phosphate backbone. | Working/Explanation: Ligase links fragments together to create a continuous, solid DNA strand [39], [41].

Semi-Conservative Replication

Each new DNA molecule contains one original parent strand and one newly synthesised strand. | Working/Explanation: This ensures that the genetic information is copied accurately from the original template [39], [42].

Purpose of Mitosis

For growth and repair of body cells. | Working/Explanation: Mitosis produces new cells that are genetically identical to the parent cell [43], [44].

Daughter Cells in Mitosis

Two identical diploid (2n) daughter cells. | Working/Explanation: The resulting cells have the same number of chromosomes (46 in humans) as the parent cell [43], [44].

Purpose of Meiosis

To produce gametes (sperm and eggs) for reproduction. | Working/Explanation: Meiosis reduces the chromosome number by half to ensure genetic variation in offspring [43], [45].

Daughter Cells in Meiosis

Four unique haploid (n) daughter cells. | Working/Explanation: These cells have half the chromosome number (23 in humans) and are genetically different from each other [43].

Define Gene

A section of DNA that codes for a particular trait/protein. | Working/Explanation: Genes are the individual instructions within a chromosome [32], [46].

Define Allele

An alternative form of a gene. | Working/Explanation: For example, for the "eye color" gene, one allele might code for blue and another for brown [32], [47].

Define Homozygous

Having two identical alleles for a particular gene (e.g., RR or rr). | Working/Explanation: Also known as "pure-breeding" for that specific trait [48], [49].

Define Heterozygous

Having two different alleles for a particular gene (e.g., Rr). | Working/Explanation: Also known as a "hybrid" [48], [49].

Define Genotype

The genetic make-up of an individual (the alleles they possess). | Working/Explanation: Represented by letters, such as BB, Bb, or bb [47], [48].

Define Phenotype

The physical characteristic or trait expressed by an organism. | Working/Explanation: The phenotype (e.g., brown eyes) is determined by the genotype and the environment [47], [48].

Dominant Allele

An allele that is always expressed in the phenotype if present. | Working/Explanation: Represented by a capital letter (e.g., B); it masks the recessive allele [47], [48].

Recessive Allele

An allele that is only expressed in the phenotype if the individual is homozygous recessive. | Working/Explanation: Represented by a lowercase letter (e.g., b); it is hidden by a dominant allele [47], [48].

Autosomal Inheritance

Inheritance of genes located on the non-sex chromosomes (pairs 1-22). | Working/Explanation: Traits are passed equally to males and females [47], [48].

Sex-Linked Inheritance

Inheritance of genes located on the sex chromosomes (X or Y). | Working/Explanation: Most sex-linked traits are on the X chromosome and appear more frequently in one sex [47], [48].

Mutations and Variation

Mutations are the source of new alleles and genetic variation in a population. | Working/Explanation: A mutation is a change in the DNA base sequence [29].

Natural Selection: Selection Pressures

Environmental factors that favor certain traits over others. | Working/Explanation: Examples include predators, disease, or climate change [29].

Natural Selection Mechanism

Variation exists -> selection pressure applied -> individuals with favorable traits survive and reproduce -> traits passed to next generation. | Working/Explanation: This process leads to the adaptation of a population over time [29].

Allopatric Speciation

Speciation that occurs due to geographic isolation. | Working/Explanation: A physical barrier (like a mountain or ocean) prevents groups from interbreeding [50].

Sympatric Speciation

Speciation that occurs without geographic isolation. | Working/Explanation: Populations evolve into separate species while living in the same geographic area, often due to behavioral or reproductive differences [50].