Reflection, Matter and Living Organisms

Choose the best answer for each question.

1. A ray of light makes an angle of 32° with the surface of a plane mirror. What is its angle of reflection?
   1. 32°
   2. 58°
   3. 64°
   4. 148°
2. The angle between an incident ray and its reflected ray is 74°. What is the angle of incidence?
   1. 16°
   2. 37°
   3. 53°
   4. 74°
3. The angle of incidence of a ray increases from 25° to 40°. Which statement is correct?
   1. The angle of reflection increases by 15°, and the angle between the incident and reflected rays increases by 30°.
   2. The angle of reflection increases by 30°, and the angle between the incident and reflected rays increases by 15°.
   3. The angle of reflection decreases by 15°.
   4. The angle between the incident and reflected rays remains unchanged.
4. A pure substance contains only one type of atom. Some of its particles contain two atoms joined together. How should the substance be classified?
   1. An element
   2. A compound
   3. A mixture
   4. A metal compound
5. Substance X is a pure substance that can be broken down chemically into two simpler substances. Neither simpler substance can be broken down chemically. What is substance X?
   1. An atom
   2. An element
   3. A compound
   4. A mixture
6. Four samples are described below. Which sample must be a mixture?
   1. It contains only one type of atom.
   2. It has a fixed composition and cannot be broken down chemically.
   3. It contains two substances that retain their own properties.
   4. It contains two types of atoms chemically joined in a fixed ratio.
7. Which statement correctly compares a compound with a mixture?
   1. Both must contain their components in a fixed ratio.
   2. A compound is always an element, but a mixture is not.
   3. The components of a mixture retain their properties, but the elements in a compound form a substance with new properties.
   4. A mixture contains only one type of particle, while a compound contains several types.
8. An unknown solid is shiny, can be hammered into a thin sheet and conducts electricity well. The solid is most likely:
   1. a metal because it is lustrous, malleable and electrically conductive.
   2. a metal because all metals are soft.
   3. a non-metal because it can be shaped.
   4. a non-metal because shiny substances do not conduct electricity.
9. Which set of properties is most typical of a solid non-metal?
   1. Shiny, malleable and a good conductor
   2. Dull, brittle and a poor conductor
   3. Shiny, ductile and a poor conductor
   4. Dull, malleable and a good conductor
10. A student investigates how the amount of fertiliser affects the growth of bean plants. She changes the amount of fertiliser and measures the increase in plant height after three weeks. What is the dependent variable?
    1. The type of bean plant
    2. The amount of fertiliser
    3. The increase in plant height
    4. The length of the investigation
11. A student investigates whether water temperature affects how quickly sugar dissolves. Which variable should be kept constant to make the investigation fair?
    1. The temperature of the water
    2. The time taken for the sugar to dissolve
    3. The amount of sugar used
    4. The measured dissolving time
12. A plant shoot bends towards a light source. Which characteristic of living organisms is demonstrated most directly?
    1. Growth
    2. Nutrition
    3. Sensitivity
    4. Excretion
13. Which observation provides the strongest evidence of growth in a young plant?
    1. Its leaves move in the wind.
    2. Its permanent dry mass increases.
    3. Water collects on the surface of its leaves.
    4. Its shoot bends towards light.
14. Which process is an example of excretion?
    1. Removing undigested food from the body
    2. Releasing carbon dioxide produced by cells
    3. Taking food into the body
    4. Breaking food into smaller pieces
15. A student wants to investigate whether light intensity affects the movement of woodlice. Which is the best experimental design?
    1. Change light intensity and humidity together, then count the woodlice in each area.
    2. Change light intensity, keep other conditions constant and measure the number of woodlice in each area after a fixed time.
    3. Keep light intensity constant and change the number of woodlice.
    4. Use different species of woodlice under different light intensities.

Write “True” or “False” for each statement. If a statement is false, rewrite it correctly.

1. The angle of incidence is measured between the incident ray and the surface of the mirror.
2. According to the laws of reflection, the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
3. If an incident ray makes an angle of 24° with a mirror surface, the angle between the incident ray and the reflected ray is 132°.
4. Every particle of an element contains only one type of atom, although a particle may contain more than one atom.
5. A compound contains two or more elements chemically combined in a fixed ratio.
6. The substances in a mixture lose their original properties and form a new substance.
7. If two pure substances contain the same elements but in different fixed ratios, they may be different compounds.
8. Metals are generally good conductors of heat and electricity, while solid non-metals are generally poor conductors.
9. A substance must be a metal if it has a shiny surface.
10. The independent variable is the variable that is deliberately changed by the investigator.
11. The dependent variable should be kept unchanged throughout an investigation.
12. Control variables are conditions kept constant so that changes in the dependent variable can be linked more confidently to the independent variable.
13. Respiration is a chemical process in cells that releases energy from food.
14. An organism demonstrates movement only when its whole body moves from one place to another.
15. A flowering plant producing seeds demonstrates reproduction.

Complete each statement with the most appropriate word, phrase or numerical value.

1. The imaginary line drawn perpendicular to a reflecting surface at the point where a ray strikes is called the ______________________________.
2. A ray makes an angle of 41° with a plane mirror. Its angle of reflection is ______________________________.
3. The angle between an incident ray and its reflected ray is 96°. The angle of incidence is ______________________________.
4. The smallest particle of an element that retains the chemical properties of that element is an ______________________________.
5. A pure substance containing only one type of atom is called an ______________________________.
6. A pure substance containing two or more elements chemically joined in a fixed ratio is called a ______________________________.
7. A sample containing two or more substances that are not chemically combined is a ______________________________.
8. The ability of a metal to be hammered or pressed into thin sheets is called ______________________________.
9. A material that allows electric current to pass through it easily is described as a good electrical ______________________________.
10. In an investigation, the variable deliberately changed by the investigator is the ______________________________ variable.
11. The variable measured as the result of an investigation is the ______________________________ variable.
12. Temperature, volume and duration may need to be kept constant as ______________________________ variables.
13. The process by which an organism takes in and uses materials needed for energy, growth and repair is called ______________________________.
14. A change in the position of part or all of an organism is called ______________________________.
15. The removal of toxic materials and waste products made by an organism is called ______________________________.