Science Half Yearly- YR 8

Question 1

outline the structure of a typical scientific report.

Answer 1

Heading, Purpose, Hypothesis, Materials, Procedure, Results, Practical Review, Resource List.

Question 2

Describe what each of the structures of a scientific report is.
- Heading, Purpose, Hypothesis, Materials, Procedure, Results, Practical Review, Resource List.

Answer 2

• Heading- the name and date of the investigation and a list of partners in your team.
  -Purpose- or aim is where you describe briefly what you are trying to do
  -Hypothesis- an educated guess about what might happen in an experiment and what might be found out.
  -Materials- a comprehensive list of everything that you used in the investigation. This includes chemicals used (formulas and concentration/ quantity), and equipment or apparatus used (correct sizes).
  -Procedure- or method is a description of everything that you did in the investigation.
  -Results- complete list of your observations and your measurements (in a table). This is where you can start analysing your data such as calculating averages, spreadsheet, diagrams and graphs can also display this data.
  -Practical Review- or discussion where you discuss your experiment. You describe what happened and why, what you think the results show, include related second-hand data, describe the problems encountered and what was done to overcome them, a conclusion of what you found out in your investigation and asses your investigation which includes whether your hypothesis was correct, suggesting alternative procedures that may improve the investigation and ideas for future experiments.
  -Resource List- of all second-hand data used/ bibliography

Question 3

what is an independent, dependent and controlled variable?

Answer 3

independent variable- is the variable you have control over and decide the way it changes.
Dependant variable- is the variable that you measure.
Controlled variable- is the variable that could change but you need to keep the same to make it a fair test.

Question 4

explain how reliability, validity and safety have been considered in a first-hand investigation.

Answer 4

Reliable data is how many times you repeat the experiment and come to similar results. If the results of an experiment are consistent across many repetitions, then the experiment is deemed reliable. (the Reliability has R for Repeats).

Valid data is about how well you have controlled your experimental variables in order to maintain a fair test. (think Valid and a V or Variables)

The safety investigation process for investigating the experiment’s possible hazards or risks. eg. risk assessment to ensure the experiment is safe to carry out.

Question 5

what is kinetic energy?

Answer 5

Kinetic energy is the energy of movement. Anything that moves has kinetic energy. The faster an object moves, the more kinetic energy it has.

Question 6

what is heat energy

Answer 6

heat energy can come from the sun, flames, chemical reactions, electrical devices or even from a person or animal. Heat warms, burns, dries, melts and makes hot air balloons rise.

Question 7

what is light energy

Answer 7

light energy comes from the sun, light globes, fires and animals such as glow worms. Without light energy, the world would be a very dark place.

Question 8

what is sound energy

Answer 8

sound energy is the energy that air has when it’s vibrating. Your ears and brain interpret the vibrating of air as sounds. Sounds come from your voice, musical instruments, cars and power tools.

Question 9

what is electrical energy

Answer 9

electrical energy is produced by power stations, solar cells, batteries and lightning. Electrical energy powers your TV, computer, microwave and toaster.

Question 10

define potential energy as a stored energy and give an example.

Answer 10

Many of the objects around you have stored energy or potential energy. It is not in use at the moment but has stored energy and gives objects the potential to make things happen. eg. a form of potential energy is the chemical energy your body gains from eating food which enables you to do certain activities.

Question 11

What is gravitational potential energy and give an example?

Answer 11

gravitational potential energy is energy stored in an object when it is above ground. The greater the height, the more gravitational potential energy an object has. eg. The higher a water slide, the gravitational potential energy you have at the top and the more kinetic energy on the way down.

Question 12

what is chemical energy and give an example?

Answer 12

chemical energy is energy stored in substances. This energy is released by your body when you digest food and by cars when fuel is burnt. eg, wood, paper, apples, petrol and batteries.

Question 13

what is elastic potential energy and give an example?

Answer 13

elastic potential energy is energy stored in a stretched or squashed spring. Stretched rubber bands also store elastic potential energy, which is released when they are let go.

Question 14

what is nuclear energy and give an example?

Answer 14

nuclear energy is energy stored inside the tiny atoms that make up all matter. Nuclear energy is released in nuclear power plants, when a nuclear bomb explodes and inside the sun. Nuclear reactions produce heat and light.

Question 15

what are the three ways of heat energy transfer?

Answer 15

conduction, convection and radiation

Question 16

describe the transfer of heat energy by conduction and include situations in which it occurs.

Answer 16

conduction happens between two objects that are in contact. Heat transfers from the hotter object to the cooler one, until they are both the same temperature. For example, a can of cold lemonade because heat transfers from your hand to the can and the conc=duction makes your hand get colder and the e can and lemonade warmer.

Question 17

describe the transfer of heat energy by convection and include situations in which it occurs.

Answer 17

Convection is the process of heat transfer through liquids and gases. For example, you don’t need to touch a heater to feel heat transfer. Convection also spreads heat through soup being heated in a saucepan.

Question 18

describe the transfer of heat energy by radiation and include situations in which it occurs.

Answer 18

Radiation- heat radiates (spreads outwards) from any hot object. Radiant heat is transferred as a wave that can travel even through the vacuum of space. This is how you feel the heat of the sun when you are outside, Radiation can be easily blocked. eg. standing in the shadow of a tree feels much cooler.

Question 19

Explain that energy can be converted or transported from one type to another and give everyday examples.

Answer 19

Energy can be transferred from one object to another but also changed or transformed from one to another type of energy. Some examples include the electrical energy of a toaster transforming into heat energy or a car’s chemical energy transform into kinetic, sound and heat energy. Sometimes a number of different energy changes happen all at once.

Question 20

what is used to measure energy

Answer 20

joule (J)

Question 21

Define energy efficiency as the percentage of the energy put into a task that results in the task being completed.

Answer 21

Any device that converts energy, such as a car or a computer, requires some form of energy to make it run. This is its input, useful energy is its output. Unfortunately, unwanted forms of energy are released too, usually as heat. Energy efficiency is a measure of how much input energy is converted into useful output energy. The greater the proportion of useful output energy, the greater the energy efficiency of the device. If most of the input energy is converted into useful output, then the device is energy efficient. If most of the input energy is wasted, then the device is inefficient.

Question 22

how do you calculate energy efficiency given relevant data

Answer 22

energy efficiency = useful energy output divided by energy input times 100.

Question 23

Identify design features of modern homes that improve energy efficiency and reduce energy waste/ greenhouse gas production.

Answer 23

considering the orientation of windows- placing large windows along the northern and eastern sides of the house, with small or no windows on the hot western side and cooler southern side.

considering the orientation of the house and the block of land- having living areas facing north and other rooms (such as bathrooms) facing south.

• tinting or shading west-facing windows
• including coverings such as eaves, verandas or pergolas over north and west-facing windows
• Insulating the floor, walls and roof to reduce energy losses.

Question 24

identify appliances that improve energy efficiency.

Answer 24

magnetic refrigeration is a new way of providing cooling using a magnetic field, LED’s produce very little heat and are extremely energy efficient, organic photovoltaics are a new generation of flexible and cheap collar cells made from carbon-based materials, dry washing machines use only a small amount of water and much less energy is required to pump water in or out of a normal washing machine. The water does not need to be heated.

Question 25

what is needed to create a simple circuit?

Answer 25

• an energy source, such as a battery, a power point or a generator. This supplies the electrons in the wire with the energy they require to get them moving around the circuit.
• an energy user, such as a light globe, heating element or motor. These devices convert the energy that electrons are delivering to them.
• wires to connect everything, making the circuits complete.

Question 26

How to calculate the total magnification of a microscope?

Answer 26

As some microscopes have two lenses, an eyepiece or ocular lens and an objective lens. To calculate the total magnification, you multiply the magnification of the ocular lens by the magnification of the objective lens.

Question 27

describe the parts of an animal cell.

Answer 27

Nucleus-
cell membrane-
cytoplasm-
vacuole- there may be several very small vacuoles in an animal cell. They may contain wastes or chemicals that are being moved around the cell.

Question 28

describe the parts of the plant cell.

Answer 28

Nucleus-
cell membrane-
cytoplasm-
vacuole- the vacuole in plant cells is large and occupies most of the cell. It is filled with sap and stores water, wastes and nutrients. When it is full, the vacuole pushes against the cell wall and helps to keep the plant rigid.
cell wall-
chloroplast-

Question 29

Describe the function of the shared cell organelles: nucleus, cell membrane and cytoplasm

Answer 29

nucleus- the control centre of the cell. It controls all the chemical reactions in the cell, how the cell develops and how it reproduces.

cell membrane- the ‘skin’ that holds the cell together. It controls what comes into and leaves the cell.

cytoplasm- a watery, jelly-like mixture that contains many smaller parts where the work of the cell takes place.

Question 30

Describe the function of the plant cell organelles: cell wall and chloroplast.

Answer 30

cell wall- plants do not have a skeleton, so they need something else to keep them upright and to keep their shape. This is the function of the cell wall, which lies outside the cell membrane.

chloroplast- chloroplasts are only found in plant cells and only in the green parts of plants. Chloroplasts are the site of photosynthesis.

Question 31

Define the term unicellular

Answer 31

Living things that are made up of only one cell are known as unicellular organisms. Bacteria are unicellular organisms, some causing disease and infection but others live on and in your body to help you stay healthy. Unicellular organisms belong to a group called the protists and many different types of unicellular organisms live in watery environments.