science yearly

Comprehensive review flashcards covering energy systems, electrical circuits, homeostasis, infectious and non-infectious diseases, chemical bonding, organic chemistry, and polymers.

What is the difference between an energy source and an energy type?

An energy source is the natural resource or raw material used to create power, whilst an energy type is the physical manifestation of that energy categorized by how it behaves.

State the Law of Conservation of Energy.

Energy can be transferred, transformed or stored, but it cannot be created or destroyed in a closed system.

How do energy transfer and energy transformation differ?

Energy transfer is the movement of energy from one location to another, whereas energy transformation is when a device changes one energy type into another.

What energy transformations and wasted energies occur in an electric kettle and a torch?

Kettle: transforms electrical energy to thermal energy; sound and thermal are wasted. Torch: transforms chemical to electrical to light energy; thermal is wasted.

How is energy efficiency defined?

Energy efficiency is the percentage of useful energy obtained from an amount of supplied energy.

What are the standard conventions for drawing a Sankey diagram?

Input energy enters on the left, useful energy exits along the top right, and wasted energy is directed downward, with energy types and values stated with units.

How do conduction, convection, and radiation transfer thermal energy?

Conduction is transfer through direct contact; convection is heat transfer through the movement of a liquid or gas (warm fluid rises and cold sinks); radiation is heat transfer through electromagnetic waves without needing a medium.

What equation is used to calculate work done?

$$\text{Work done} = \text{Force} \times \text{Distance}$$

Describe how electricity is generated in a coal or gas power station using its key components.

Fuel is burnt in a furnace to create heat, a boiler turns high-pressure water into steam, and the steam spins turbines that drive a generator.

What energy transformations occur in a nuclear power station?

$$\text{Nuclear} \rightarrow \text{Thermal} \rightarrow \text{Kinetic} \rightarrow \text{Electrical}$$

What are the roles of fuel rods, control rods, and coolant water in a nuclear reactor core?

Fuel rods undergo nuclear fission when atoms split to release thermal energy; control rods absorb neutrons to control the reaction rate; water acts as a coolant by absorbing thermal energy to generate steam.

Define electrical charge, current, voltage, and resistance, including their units.

Charge is the number of electrons in an area (Coulombs, $\text{C}$); Current is the flow of charge (Amps, $\text{A}$); Voltage is the energy per electron to do work (Volts, $\text{V}$); Resistance is the opposition to charge flow (Ohms, $\Omega$).

State Ohm's Law.

When a resistor is kept at a constant temperature, its resistance will remain unchanged ($V = I \times R$).

How do total voltage and total current behave in series versus parallel circuits?

Series: $V_{\text{total}} = V_1 + V_2$ and $I_{\text{total}} = I_1 = I_2$. Parallel: $V_{\text{total}} = V_1 = V_2$ and $I_{\text{total}} = I_1 + I_2$.

What formulas express electrical power?

$P = \frac{E}{t}$ (energy transferred per second) and $P = V \times I$.

Define homeostasis.

Homeostasis is the maintenance of an internal environment within tolerance limits.

Why is an internal body temperature of $37\,^\circ\text{C}$ maintained in humans?

$37\,^\circ\text{C}$ is the optimum temperature for enzymes involved in cellular processes, specifically cellular respiration ($\text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy}$). At higher temperatures, these proteins denature and lose their shape.

How does breathing excrete carbon dioxide to maintain a stable blood pH?

Carbon dioxide decreases blood pH, making it more acidic. Exhaling $CO_2$ through gas exchange removes it; steady breathing maintains stable blood pH levels.

What are the stimulus, receptor, control centre, effectors, and response in thermoregulation when body temperature rises?

Stimulus: increase in body temperature; Receptor: thermoreceptors; Control centre: hypothalamus; Effectors: blood vessels undergo vasodilation and sweat glands secrete sweat; Response: decrease in body temperature.

How does the pancreas regulate high versus low blood glucose levels?

High glucose: beta cells release insulin, signaling the liver to absorb glucose and store it as glycogen. Low glucose: alpha cells release glucagon, stimulating the liver to convert glycogen to glucose and release it into the blood.

Identify the labelled structures A through F on the neuron diagram.

A: Dendrite, B: Cell body (soma), C: Axon hillock, D: Myelin sheath, E: Node of Ranvier, F: Synapse / Axon terminal.

Trace the pathway of a nerve impulse in an arc reflex response to pain.

$\text{Stimulus} \rightarrow \text{sensory neuron} \rightarrow \text{spinal cord} \rightarrow \text{motor neuron} \rightarrow \text{effector organ} \rightarrow \text{response}$ (bypasses a conscious brain control centre).

Distinguish between the signaling speed and duration of the nervous system versus the endocrine system.

The nervous system sends rapid electrochemical impulses that last for a short time. The endocrine system secretes hormones into the bloodstream, which take longer to transmit but produce effects that last for long periods.

How are viruses, bacteria, fungi, and macro-parasites classified by cellular structure?

Viruses: non-cellular, no membrane or nucleus. Bacteria: unicellular, cell membrane, no nucleus. Fungi: unicellular or multicellular, cell membrane and nucleus. Macro-parasites: multicellular, cell membrane and nucleus.

What are the components of the body's first line of defence?

Physical barriers: skin (sheds cells) and mucus (traps pathogens). Chemical barriers: stomach acid (low pH dissolves swallowed microbes) and acidic urine flushing the urinal genital tract.

What non-specific responses constitute the body's second line of defence?

Inflammation (brings white blood cells to damaged tissue), fever (raised temperature inhibits pathogen survival), and phagocytosis (phagocytes engulf and enzymatically destroy foreign particles).

How do B cells and memory cells provide immunity in the third line of defence?

B cell receptors recognize matching foreign antigens, activating B cells to divide into plasma cells (which produce antibodies) and memory cells. Memory cells remain in the blood to trigger a faster, stronger secondary immune response upon reinfection.

What are the three categories of non-infectious diseases and an example of each?

Genetic (e.g., sickle cell anaemia), Environmental (e.g., melanoma), and Nutritional (e.g., scurvy).

Distinguish between Type 1, Type 2, and gestational diabetes.

Type 1: autoimmune attack on insulin-producing beta cells. Type 2: body cells become less responsive to insulin and the pancreas does not produce enough. Gestational: develops during pregnancy and usually resolves after birth.

What are cations and anions, and which elements typically form each?

Cations are positively charged ions formed when atoms lose electrons (typically metals). Anions are negatively charged ions formed when atoms gain electrons (typically nonmetals).

Define ionic bonding.

Ionic bonding is the electrostatic attraction between oppositely charged ions formed when a metal atom transfers electrons to a nonmetal atom.

Define covalent bonding.

Covalent bonding is the chemical link formed between two nonmetal atoms that share one or more pairs of valence electrons to achieve a noble gas configuration.

How does metallic bonding explain the electrical conductivity and malleability of metals?

Metallic bonding consists of a lattice of cations surrounded by a sea of delocalised electrons. Free-moving delocalised electrons easily conduct electricity. When hammered, cation layers slide past one another while the electron sea shifts alongside them, preventing shattering.

How does fractional distillation separate hydrocarbons from crude oil?

Crude oil is vaporized and enters a fractionating column that is hot at the bottom and cooler at the top. Hydrocarbons condense and are collected at different heights according to their boiling points (short chains have lower boiling points; long chains have higher boiling points).

What are the IUPAC root prefixes for carbon chain lengths 1 through 10?

1: meth, 2: eth, 3: prop, 4: but, 5: pent, 6: hex, 7: hept, 8: oct, 9: non, 10: dec.

How do complete and incomplete combustion differ in reactants, products, and flame appearance?

Complete: fuel + plenty of oxygen produces carbon dioxide + water, releases more energy, and burns with a blue flame. Incomplete: fuel + limited oxygen produces carbon monoxide + soot (carbon) + water, releases less energy, and burns with a yellow/orange smoky flame.

What occurs during addition polymerisation of ethene to polyethene?

Many small monomer molecules of ethene join together as carbon-carbon double bonds open up to link into one long polyethene polymer chain.

Define the term biodegradable.

A material that can be broken down naturally by microorganisms, such as bacteria, into simpler substances.