NGSS:
HS-LS1-3: Plan and conduct investigation to provide evidence
that feedback mechanisms maintain homeostasis
 SWBAT:
 Identify how biological processes are regulated by
negative and positive feedback mechanism while
watching a video
 Analyse the elements of a feedback system, and
create a flowchart to model the feedback system of
given cases.

Warm-Up
Recall reproductive system and analyze the negative feedback in the
flow chart below:
https://www.youtube.com/watch?v=R6_oe_QcHKc&t=2s
 Watch the video ,take individual active notes ,discuss
with your group then share to the class.
 What is the benefit of feedback mechanism on
human body?
 Compare between negative and positive feedback
with examples.
Case Studies/Scenarios
 Create a simple flow chart on A3 paper , identify all the
components of feedback mechanism of given cases.
Stage 1 – Preparation. Each group reads a case study ,answer the
questions then create a poster. You will write down the most
important points
Stage 2 – Part of group the will stay with poster, to explain their
information to visiting researchers. Two members of the group
will be visiting the next group to get information
Stage 3 – Teaching. The researchers explain their findings to their
original groups.
Students will record their notes in their copy books
Brain stimulates pituitary
gland to secrete oxytocin
Childbirth
Task 1:
Oxytocin carried in
bloodstream to uterus
Nerve impulse from cervix
transmitted to brain.
Oxytocin stimulates
uterine contractions
and pushes fetus
towards cervix.
Head of fetus pushes against cervix
1)State whether it is a positive or negative feedback. Explain your answer
2)Identify the gland involved and describe the mechanism and the importance
on maintaining homeostasis.
3)3)Extension
Using evidence from the graph below, give examples of positive and
negative feedback in the human ovarian cycle.
Osmoregulation
Osmoregulation refers to the control of the
concentration of various liquids within the
body, to maintain homeostasis in case of too
much water in blood.
1)State whether it is a positive or negative
feedback. Explain your answer
2)Identify the gland involved and describe the
mechanism and the importance on maintaining
homeostasis.
3)Extension
Using evidence from the graph below, give
examples of positive and negative feedback
in the human ovarian cycle.
Sugar level regulation
1)State whether it is a positive or negative
feedback. Explain your answer
2)Identify the gland involved and describe the
mechanism and the importance on maintaining
homeostasis.
3)Extension
Using evidence from the graph below, give
examples of positive and negative feedback
in the human ovarian cycle.
1)State whether it is a positive or negative
feedback. Explain your answer
2)Identify the gland involved and describe the
mechanism and the importance on maintaining
homeostasis.
You may use this link for extra help
https://askabiologist.asu.edu/bird-hypothalamus
3)Extension
‘Using evidence from the below graph, give
examples of positive and negative feedback
in the human ovarian cycle.
 Exit ticket:
Q:
1-What would happen to the negative - feedback
mechanism if hormones remained in the blood
rather than being carried into the target cells?For
example insulin
2-explain one feedback mechanism in your copybook
 https://quizlet.com/252205065/test
 Take the quiz