Body Systems
Put the levels of biological organisation in order from smallest to largest.
Cell organelle → Cell → Tissue → Organ → System → Organism
Which type of feedback reduces a change to maintain homeostasis?
Negative feedback
Name the three main subatomic particles of an atom.
Proton, Neutron, Electron
What is a combustion reaction?
A reaction where a substance reacts with oxygen to release heat and light.
What instrument measures current? Voltage?
Ammeter measures current; Voltmeter measures voltage
What happens to the current when measured in a series circuit versus a parallel circuit?
Series Circuit:
The current is the same at all points in the circuit because there is only one path for electrons to flow.
Parallel Circuit:
The total current splits across the different branches.
Each branch gets part of the total current, depending on the resistance of that branch.
Name one way the digestive system interacts with the circulatory system.
Nutrients absorbed by intestines enter blood vessels to be transported to cells.
Give one example of a negative feedback loop in the human body
Body temperature regulation; insulin/glucose regulation.
What is the atomic number of an element?
The number of protons in the nucleus of an atom
Calcium has an atomic number of 20. What charged ion does it commonly form, and why?
Calcium commonly forms a Ca²⁺ ion.
This happens because it loses 2 electrons to achieve a full outer electron shell (stable noble gas configuration).
Losing electrons gives it a positive charge (+2).
State Ohm’s Law
V = I × R (Voltage = Current × Resistance)
What is the difference between ground state and excited state of an electron?
Ground state: lowest energy level; Excited state: electron absorbs energy and moves to a higher level.
What is the main function of the nervous system in body coordination?
To send and receive electrical signals to control body functions and responses to stimuli.
What is positive feedback? Give one example
a process where a change triggers a response that amplifies the original change.
Oxytocin in the process of childbirth
Define isotope
Atoms of the same element with the same number of protons but different numbers of neutrons.
What type of radiation is released during nuclear decay?
Alpha, beta, or gamma radiation.
What is the purpose of a fuse in an electrical circuit?
To protect the circuit by breaking the flow of excessive current.
How can the periodic table predict properties of elements in the same group?
Elements in the same group have similar valence electron configurations, leading to similar chemical properties.
Define homeostasis and give one example in the human body.
Maintaining a stable internal environment; e.g., regulating body temperature, blood glucose, or water balance.
What is the difference between the central and peripheral nervous system?
CNS - Brain and spinal cord
PNS - Peripheral nerves ie. everything else
Describe the arrangement of electrons in the first 3 shells of an atom.
1st shell: 2
2nd shell: 8
3rd shell: 8
Why are flame tests useful in chemistry?
They identify elements based on the characteristic colour produced when electrons return to ground state.
What is the difference between series and parallel circuits?
Series: components in a single path; Parallel: components in multiple paths.
Explain how the digestive system and circulatory system work together to provide energy to the body.
The digestive system breaks down food into nutrients, such as glucose, amino acids, and fatty acids.
These nutrients are absorbed into the blood through the walls of the small intestine.
The circulatory system then transports these nutrients to cells throughout the body, where they are used in cellular respiration to release energy.
Describe a reflex arc and explain why reflexes are faster than voluntary responses.
A reflex arc involves sensory neurons → spinal cord → motor neurons, bypassing the brain for faster response to protect the body.
What is the main function of the stomach in the digestive system?
The stomach breaks down food using acids and enzymes, turning it into a semi-liquid called chyme.
It also kills bacteria and begins the digestion of proteins.
How can the periodic table predict properties of elements in the same group?
Elements in the same group have similar valence electron configurations, leading to similar chemical properties.
What is the difference between a neutral atom and a charged ion?
Neutral atom: Has the same number of protons and electrons, so it has no overall charge.
Charged ion: Has gained or lost electrons, so it has a positive charge (cation) if electrons are lost, or a negative charge (anion) if electrons are gained.
How can energy efficiency be improved in an electric circuit?
Reduce resistance, use efficient appliances, minimise energy loss as heat.
Explain why AC is used for household supply, but DC is often used in electronics.
AC can be easily transformed to high voltages for transmission and back to low voltages; DC is stable and preferred for electronics.