4.4 Special food relationships

Natural sciences

Grade 8

Environment and interactions

Module 36

Special food relationships

Activity:

To be able to identify special food relationships and to be able to describe them from examples

[lo 2.4]

Besides the typical predator and prey relationships there are certain relationships that are very interesting and special, especially because they are also linked to survival strategies.

SYMBIOSIS is the co-existence of two different organisms.

This relationship of co-existing can differ with regard to the amount of advantage or disadvantage gained by each party.

Commensalism

• 

  One of the organisms benefits and the other one is not really affected.

Mutualism

• Both organisms benefit.

Parasitism

• One organism definitely benefits at the expense of the other one.

Complete the table by pasting one of the sketches from the sketch sheet next to each of the relationships. Paste in some of your own examples as well. Describe the characteristics of the relationship in the right-hand column.

Special Food Relationships

Assessment of CUTTING AND PASTING of SYMBIOSIS SKETCHES

Were you able to identify and describe SYMBIOSIS TYPES correctly?

[LO 2.4]

Activity:

To do research on parasitism and to represent the results graphically on a poster

[lo 1.1; lo 1.2; lo 1.3]

Work in groups of four and collect examples of the different kinds of parasites that use both humans and animals as hosts.

• Explain the following:

1. the parasite and the host, and the nature of their relationship

2. symptoms that can be detected in the host

3. how to combat the parasite

• Divide the different parts of the assignment among the members of the group so that each one will be responsible for a certain part.
• Remember that plants also have parasites – find out more about this and use at least one plant as an example. Present the poster to the rest of the class.

Assessment of GROUP WORK, RESEARCH AND COMMUNICATION on PARASITES

Were you able to contribute to the group’s research work, and communicate it to the

rest of the class? LO 1.1 ; LO 1.2; LO 1.3

Assessment

LO 1: Scientific investigations:

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

This is evident when the learner:

• plans investigations;
• conducts investigations and collects data;
• evaluates data and communicates findings.

LO 2: Constructing Science Knowledge:

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

This is evident when the learner:

2.4 applies knowledge.

Memorandum

Activity: Special food relationships

Mutualism : bird and flower: The bird obtains food (advantage), flower is pollinated (advantage).

Parasitism : tick on horse: The tick obtains food (advantage), horse loses blood (disadvantage).

Commensalism : Cattle and birds: Cattle dislodge and carry ticks that occur on the grass, providing food for the birds while the cattle remain unaffected.

Sharks and small fish: The fish eat the remains of the food consumed by the sharks while the sharks remain unaffected.

Activity: Researching parasitism

• Assess the learner's attempt in terms of the three assessment standards 1.1 (planning), 1.2 (collecting data), and 1.3 (interpretation and communication).