6.3 Proper Handling of Radioactive Substances

6.3 Proper Handling of Radioactive Substances

6.3.1 Effects of Radioactive Radiation on Living Things
1. Radioactive substances are highly hazardous.
2. The energy in radiation can destroy molecules in living tissues and kill cells.
3. The effects of radioactive radiation on living things depend on the total amount of radiation received.
4. Diagram below shows effects of exposure to radioactive radiation over different period of time:

6.2.3 Process of Generating Electricity from Nuclear Energy

6.2.3 Uses of Nuclear Fusion
1. Nuclear energy is used to
(a) Generate electrical energy
(b) Operate satellites
(c) Propel cruises, aircraft carriers and submarines

Nuclear power station

6.2.4 Process of Generating Electricity from Nuclear Energy
1. In a nuclear power station, nuclear energy is produced in a nuclear reactor to generate electricity.
2. Figure below shows the main components in a nuclear power station.

 Nuclear power station

Graphite moderator
Fast moving neutrons are slowed down by collisions with nuclei in the moderator so that they can cause further fission. In some nuclear power plant, the moderator is water.
b.  Uranium rod (Fuel)
Produces nuclear energy from chain reactions of nuclear fission.
c.  Control rod
Control the rate of chain reaction.
d.  Coolant
To take away the heat from the nuclear reactor.
e.  Thick concrete wall
To prevent the escape of harmful radiations.
f.   Steam generator
Water in the generator is heated and changed into steam. The steam then drives the turbines.
g.  Turbine
To turn the dynamo in the electrical generator to produce electricity.

3. Figure below shows the summary of the process taking place and transformation of energy in a nuclear power station.

Energy transformation during generation of electricity

8.7.1 The Abiotic and Biotic Components of the Environment (Structured Question 1 & 2)

[adinserter block="3"]
Question 1:
R, S and T in Figure below show three types of interactions between organisms.

Name the type of interaction represented by R and S.

Describe the interaction represented by R.
[adinserter block="3"]

In the interactions represented by S and T, what terms are used to describe organisms X and Y?

State one characteristics of organism X that adapts it for the interaction.

The rubber tree in the interaction represented by S dies.
Explain what will happen to organism X.

Saw dust can be used in the interaction represented by T for the commercial cultivation of mushrooms.
Explain how mushrooms can grow on saw dust.

[adinserter block="3"]
Organism R: Mutualism/ symbiosis
Organism S: Commensalism

Nitrogen-fixing bacteria in the root nodules fix nitrogen to form ammonia which is used by the plant while Rhizobium bacteria get shelter from the plant.
[adinserter block="3"]

X: Epiphyte
Y: Saprophyte

The presence of aerial roots which absorb moisture from the air

X continues to grow because it photosynthesises.

Mushrooms grow on dead organic matter.
Mushrooms secrete enzymes which digest the complex organic matter to simple substances.

[adinserter block="3"]