1. SUBMITTED BY,
VIDYA P.PILLAI
B.Ed, IInd SEM
NATURAL SCIENCE
N. S. S. TRAINING COLLEGE
PANDALAM
SUBMITTED TO,
Dr. PADMA PRIYA
OPTIONAL IN CHARGE
NATURAL SCIENCE
N. S. S. TRAINING COLLEGE
PANDALAM

2. CONTENT
BLOCK – AN ADDRESS FOR LIVING BEINGS
TOPIC – BIOLOGICAL INTERACTIONS

3. Ammu and Achu were discussing about different types of relations among organisms.
Achu, next week i have to present a seminar
on different types of relation among
organisms. But i don’t know anything about
the topic. Can you help me please ?
Yes of course, You don’t
worry. I will help you.
Oh, Thank you
Ammu, different types of
relations are found among
organisms of various types. You
know the purpose behind that ?

4. Yes, these relationships are useful
for ensuring food and space for
living.
Yes, you are right. An animal has to depend
on other organisms in the habitat for food,
shelter, reproduction and other needs. This
type of relations exist among organisms are
known as biological interactions.
Which are the different types of
biological interactions?

5. The interactions may be of two types
interspecific or intraspecific. If the
interaction is among the individual of
same species it is called intraspecific
interaction. So, can you explain what is
interspecific interaction?
.
If the interaction is among the individuals
of different species, it is called
interspecific interaction. Am I right?
Yes, you are right. On the basis of
benefits and harmful effects of
organisms, the interactions can be
categorized in to two namely positive
interaction and negative interaction.

6. What is this positive interaction?
It is the interaction in which one
interacting species helps the other
either one way or on reciprocal
terms.
Oh! Which are the different types of
positive interactions?

7. Mutualism and commensalism are the
different types of positive interactions.
What is this Mutualism?
I will show you a video, you should
observe that and try to find out
how the organisms helps each
other ?

9. In this video plant helps butterfly by
giving honey and butterfly helps plant
by pollination.
Yes, you are right. So that is
Mutualism. Here the two
organisms are benefited.
Ok Ammu. Then what is
Commensalism?
I will show you a picture and try to
find out what is Commensalism?

10. VANDA AND MANGO TREE

11. Here vanda is benefited by getting a
support on mango tree and mango
tree is neither benefited nor harmed.
Yes, in Commensalism one is
benefited and the other is neither
benefited nor harmed.
So Achu, What about negative
interactions.

12. I will show you one more example
for commensalism. It is a video of
shark and sucker fish.
Oh! Who is benifited here
and how?
Here sucker fish attaches itself to
shark to move about in search of food
and thus it is benifited. shark is
neither benifited nor harmed..

14. So Achu, What about
negative interactions.
.
In negative interactions, one
interacting species is harmed. The
other may be harmed, benefited or
unaffected.
.

15. Which are the different types
of negative interactions.
Predation, Parasitism and
Competition are the different types
of negative interactions.
I know about Predation. Animals that
secure their food by killing other animals
are known as predatory animals and this
mode of feeding is termed Predation.

16. Yes, here one is benefited and the
other is harmed. The organism
which is benefited is the Predator
and one who killed is the Prey.
For example eagle and fish. Here
eagle is the predator and fish is the
prey.
Yes, I will show you a video on
how eagle catches its prey, the
fish.

18. What about parasitism and
competition.
In parasitism, one is benefited and
the other is harmed. The organism
which is benefited is the parasite and
one who harmed is the host.
That means in predation, the predator
is larger than the prey and in
parasitism the parasite is smaller than
the host.
Yes, this picture is an example
for Parasitism.

19. LORANTHUS AND MANGO TREE

20. Here, mango tree is the host and
loranthus is the parasite. So loranthus
is benifited and mango tree is harmed.
In competition, both organisms
suffer first. But the organism
which win is benefited. For
example crops and weeds.

21. CROPS AND WEEDS

22. Ammu, now are you familiar
with your seminar topic.
Yes Achu. Now I am very
confident to present my
seminar.
Now can you consolidate the
topic.
Yes, of course

23. CONSOLIDATION
 Different types of relationships are found among organisms of various types.
 The relationships can be categorized in to two, namely positive and negative
interactions.
 In positive interaction one interacting species helps the other either one way
or on reciprocal terms.
 In negative interactions , one interacting species is harmed. The other may be
harmed, benifited or unaffected.
 Mutualism and commensalism are the two types of positive interactions.
 Predation, parasitism and competition are the different types of negative
interactions.

24. REVIEW
• What is positive interaction?
• What is commensalism?
• Give an example for predation?
• What is parasitism?