Year 9 Science Semester 2 Exam Overview

Independent Variable

The variable changed in an experiment.

Dependent Variable

The variable measured in an experiment.

Controlled variable

variable that stays the same in a experiment

fair test

where only one variable changes

Electrostatic charge

A buildup of charges on the surface of an object

electric charge

A positive or negative charge that can be produced by protons and electrons and results in electricity

Electric circuit

A complete, unbroken path through which electric charges can flow

Conductors

Any material that allows an electric current to pass through it easily.

Insulator

A material that does not allow electrons to move through it easily.

Parallel circuit

A closed electrical circuit in which the current is divided into two or more paths and then returns via a common path to complete the circuit.

Series circuit

A circuit in which all parts are connected end to end to provide a single path of current.

Resistance

A material's opposition to the flow of electric current.

Voltage

The difference in electrical potential energy between two places in a circuit.

Current

A flow of electric charge around a circuit

Voltmeter

A device used to measure voltage, or electrical potential energy difference across components in a circuit

Ammeter

A device used to measure current in a circuit

Voltage in a parallel circuit

Same across each component

Voltage in a series circuit

Voltage is shared between components

Current in a series circuit

Same at all points

Current in a parallel circuit

Is shared between branches

Resistor

An electrical device that resists the flow of electrical current

Ohm's Law

V=IR
I=V/R
R=V/I

Ohm

unit of resistance

what charges attract

opposite charges

what charges repel

like charges

electrical conductor examples

gold copper water

Electrical insulator examples

glass rubber wood

circuit switch

circuit lamp

circuit voltmeter

circuit ammeter

circuit resistor

circuit battery

Biotic factors

living components of an ecosystem e.g grass log animals insects bacteria

abiotic factors

Nonliving components of an ecosystem eg water temperature light salinity soil

ecosystem

has living and non living stuff a system that uses and exchanges energy.

Food web

several interconnected food chains -show who eats who

producer

an organism that produces it's own energy

consumer

an organism that cannot produce it's own source of energy so it must eat other plants and/or animals to get energy

trophic levels

the position of an organism in a food web

characteristics of an ecosytem

biotic and abiotic factors, energy flow

names of trophic levels

producer, primary consumer, secondary consumer, tertiary consumer, quaternary consumer

How does the van der graaff generator work?

generates static electricity by rubbing two insulators together. One insulator transfers some of its electrons to the other, causing both to become electrically charged. The metal dome at the top of the generator collects these electrons. The electrons have nowhere to go on the dome, there is no path for them and that's why the Van de Graaff generates static electricity.

Why do styrofoam peanuts fly off the generator?

When the negative charges on the peanuts repel the negative charges on the generator, the peanuts push off the sphere.

What is static electricity?

Static electricity is the buildup of the electrical charge in an object when it is rubbed against another object

how is static electricity measured

The static charge is measured in terms of kV with a static meter

How are electrical charges created

An electrical charge is created when two materials come into contact or are rubbed together.

how can charge be conserved?

whenever charges are created there is a proton and electron which cancel each other out so the charge is always 0

static electricity v current electricity

Current is a continuous movement of charges (electrons) over time.
Static electricity is the transfer of static charges (electrons) from one surface to another due to an imbalance in charge between the surfaces.

hormone

chemical messenger in your body

adrenal gland

adrenaline and estrogen

Pancreas

glucagon (more blood sugar) and insulin (less blood sugar)

Helps you sleep

Melatonin (pinal gland)

What is homeostasis?

Maintaining a stable internal environment

What is the periphal nervous system?

nerves that runs throughout the body. It carries messages to and from the CNS

Why is the endocrine system slow acting?

Because the chemical messengers (hormones) act much slower but have longer lasting effects.

Why do hormones target certain cells

A target cell responds to a hormone because it bears receptors for the hormone (lock and key)

estrogen

Female sex hormone (ovaries)

testosterone

regulating sex drive, mood and bone and muscle strength. making blood cells.

link between endocrine and nervous system

hypothalamus

pituary gland

Multiple growth hormones

What is the Endocrine system?

A collection of glands that release hormones

Messengers in the NS
Pathway of transmission NS

nerve impulses
Neurons

Messengers in the ES
Pathway of transmission ES

Hormones
Bloodstream

How is temperature maintained at 37℃?

sweating-As the water in the sweat evaporates, the surface of the skin cools.
Blood vessel dialating -increases blood flow to the skin which helps the body to release heat through thermal radiation.

negative feedback loop

the effects of a reaction slow or stop that reaction. -sometimes reactions can be over the top negative feedback loop sorts that out

neuron

nerve cell

dendrites

collects the electrical messages.

sysnapse

gap between two neurons

what is stimuli

A change in the internal or external environment

What is an axon

Transmit impulses AWAY from cell body of neuron

What is the myelin sheath

A layer of tissue that covers axons.