Primary Lower Block
Cycles: Life Cycles
Introduction to Notes 2
The worker bees clean the
brood cells during the first
few days of their adult lives.
They then become nurse bees
who feed and care for the young.
From the 7th day, they tend
to the queen bee whose
only job is to lay eggs.
They must also dispose
of dead
bees andlike
larva in
We know
children
places
away
from
the
comics! Using that to our
beehive.
advantage, we introduce
complicated concepts in
a fun way.
Wax-producing worker
bees will need to eat 8kg
of honey to produce 1kg of
beeswax.
The beeswax produced
appears through tiny pores
in the bee’s abdomen and
will need to be chewed on
by the bees before it
becomes soft enough to be
used to repair and build
more honeycomb cells.
-1-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
Later, the young worker
bees pack and store
pollen
and
nectar
brought home by the
older foraging bees so
that they can be used as
food for the rest of the
colony.
They also help to keep
the hive cool by fanning
it with their wings using
water brought home by
the water-carrying bees.
The guard bees station
themselves near the entrance
to the hive and stand guard,
letting only family members
into the hive.
The worker bees finally ‘graduate’
from being house bees after 21
days. They are now foraging bees
and will leave the hive to gather
pollen and nectar.
* The above pictorial representations of the honey bees are for the purpose of providing information about their activities only. Please find
realistic illustrations of the bees on the next page.
-2-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
There are three types of honey bees.
The queen bee’s only job is to lay eggs. There is only one
queen bee in each honey bee colony.
The second type of honey bees are the male drones and
their job is to mate with queen bees from other colonies.
There may be several hundred drones in a colony.
The worker bees are the third type of honey bees. All the
worker bees in a colony are female and they are
responsible for all the tasks in a beehive except laying
eggs. The worker bees perform several jobs one after
another during their lifetime. The youngest worker bees take
care of the young and the queen. They then become
housekeepers and storekeepers. The older worker bees
become the guards to the hive and finally, the oldest worker
bees become gatherers which bring nectar and pollen back
from outside the hive. There are about 20 000 to 80 000
worker bees in a colony.
Different Types of Honey Bees
queen bee
worker bee
drone bee
In today’s lesson, you will learn to:

describe the four-stage life cycle of a/an:
 ladybird beetle
 mosquito
 butterfly
 ant
-3-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
Primary Lower Block
Cycles: Life Cycles
Notes 2
RECAPITULATION

A cycle is a pattern that repeats itself continuously.

A life cycle is a pattern that repeats the stages of development in the lives of the
living things.

Metamorphosis refers to the big changes in the form and habits of an animal from
birth to adult.

Animals which undergo complete metamorphosis have young that look very
different from the adult.
Example: Insects that undergo a four-stage life cycle: butterfly, ladybird beetle
egg
adult
4 stages in the
life cycle of an
insect
larva
pupa

Animals which undergo incomplete metamorphosis have young that look similar
to the adult.
Example: Insects that undergo a three-stage life cycle: grasshopper, cockroach
egg
3 stages in the
life cycle of an
insect
adult
nymph
-4-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
FOUR-STAGE LIFE CYCLES
CASE STUDY A
Life cycle of a ladybird BEETLE
Visuals help our students to
grasp the concepts quickly.
The larva feeds and
grows rapidly.
larva
2
3 weeks to
a month
About
1 week
The pupa does not
feed while its adult
structures develop.
3
pupa
egg
The tiny yellow eggs are
laid on the underside of
leaves.
About
1 week
1
The adult ladybird beetle
emerges after a week.
4
adult beetle
(2 – 3 months)

The female ladybird beetle lays its eggs on the underside of leaves.

The eggs resemble tiny yellow jellybeans.

The larva feeds on aphids, mites and even other ladybird beetle eggs.

It grows rapidly and when its body grows too big for its skin, a new skin grows
beneath the old one.

The process by which the old skin is shed is known as moulting.

The insect attaches itself to a leaf during the pupal stage.

During this stage, the pupa does not feed and there is very little movement. However,
the adult structures develop within it.

The adult beetle emerges after about a week.

The cycle repeats when the female ladybird beetle reproduces.
-5-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
As much as we would love
to show you everything,
we cannot be showing you
the best. 
Do drop by any JustEdu centre to view
the full set!
-6-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
Do drop by our centre
to view the full set of
materials.
-7-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
The monarch butterfly
The Monarch Butterfly is also known as “Milkweed Butterfly”. The Monarch butterfly only lays its eggs on the milkweed plant because its caterpillar only eats the leaves from the milkweed plant. The Monarch butterfly is poisonous and distasteful to birds and mammals. It is thought that the bright colours of the larva and adult function as warning colours. CASE STUDY D
Life cycle of OTHER INSECTS
Number of stages
3-stage life cycle
Organisms
Cricket – lays eggs in warm damp soil
Dragonfly – lays eggs in water
4-stage life cycle
cricket nymph
Bee – lays eggs within the cells in the hive
Mealworm beetle – lays eggs on leaves
-8-
mealworm beetle larva
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
Do drop by our centre
to view the full set of
materials.
The Silkworm
A silkworm is the caterpillar of the silkworm moth of the mulberry tree. They were domesticated from the wild silkworms about 2000 years ago! They are bred for the production of raw silk. In the pupa phase, the silkworms enclose themselves in cocoons made up of raw silk produced by their salivary glands. The silkworm pupae are then boiled and killed. If the moths were allowed to emerge from the cocoon, the silk will be destroyed as the moths produce enzymes that will damage the silk.
-9-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
Summary
Summarising the chapter
helps our students to recap
what has been taught during
the lesson!
1. A butterfly’s egg will hatch into a l____________ which is also known as a
c_____________________.
2. A l____________ will develop into a p____________ before it turns into an adult.
3. A mosquito l____________ is also known as a w____________.
4. A mosquito w_______________ breathes through a b___________________
t____________.
5. The process whereby the old skin is replaced by the new skin is known as
m___________________.
6. During the p____________ stage of an insect, it does not feed at all while the adult
structures are developing within it.
-10-
PSLB | Cycles | Notes 2
© JustEdu Holdings Pte Ltd
Primary Lower Block
Cycles: Life Cycles
Practice 2
Our notes are complemented
by a comprehensive Practice
paper.
A typical practice will have 15 multiplechoice questions and 5 open-ended
questions for our students to attempt.
This is then followed by an ‘ACE’
question to further enhance the
understanding of our students.
This proprietary technique is uniquely
found at JustEdu and has helped
numerous students to break down and
analyse the question before attempting.
Furthermore, this same technique can
be used to answer multiple-choice
questions as well. An example of an
‘ACE’ question is given next:
-1-
PSLB | Cycles | Practice 2
© JustEdu Holdings Pte Ltd
Use the ACE Question Answering Technique to answer the question below.
Karine placed an egg of an insect together with some food and water into a sealed
container that had some holes in its lid. After some time, she observed that the young
that had hatched from the egg did not feed or drink for a period of about a week.
However, the insect could still develop into a healthy adult.
(a) Give an example of an insect that Karine could have kept in her tank.
(b) Explain your answer in part (a).
STEP 1: ANALYSE THE QUESTION
Circle the important information in the question above. Study the question and write
down in the space below the information that you can obtain from the question.
STEP 2: CONCEPT ANCHORING
Topic: ________________________________________________________________
(a) and (b) Concepts:
 The young of an insect does not _______________ or drink during the
_______________ stage.
 The _____________-stage life cycle of an insect includes the egg, _______________,
_______________ and adult stages.
 Insects such as the _______________, ______________ and _______________
undergo a four-stage life cycle.
(b) Key points: _________________________________________________________
_________________________________________________________
-2-
PSLB | Cycles | Practice 2
© JustEdu Holdings Pte Ltd
STEP 3: ESTABLISH RELATIONSHIPS AND LINKAGES
Link the requirements in the question with the keywords listed above. You may use
arrows or a simple concept map to help you.
Answers:
(a) Give an example of an insect that Karine could have kept in her tank.
___________________________________________________________________
(b) Explain your answer in part (a).
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
-3-
PSLB | Cycles | Practice 2
© JustEdu Holdings Pte Ltd
Answers
Use the ACE Question Answering Technique to answer the question below.
STEP 1: ANALYSE THE QUESTION
Karine placed an egg of an insect together with some food and water into a sealed
container that had some holes in its lid. After some time, she observed that the young
that had hatched from the egg did not feed or drink for a period of about a week.
However, the insect could still develop into a healthy adult.
(a) Give an example of an insect that Karine could have kept in her tank.
(b) Explain your answer in part (a).
The insect young was provided with air, food and water.
STEP 2: CONCEPT ANCHORING
Life Cycles
Topic: ________________________________________________________________
(a) and (b) Concepts:
feed
 The young of an insect does not _______________
or drink during the
pupa
_______________
stage.
four
larva
 The _____________-stage
life cycle of an insect includes the egg, _______________,
pupa
_______________
and adult stages.
 Insects
such
as
the
ladybird beetle
________________________,
butterfly
______________
and
housefly
_______________
undergo a four-stage life cycle.
Four stage life cycle, young in the pupa stage
(b) Key points: _________________________________________________________
does not feed or drink.
_________________________________________________________
-4-
PSLB | Cycles | Practice 2
© JustEdu Holdings Pte Ltd
Answers
STEP 3: ESTABLISH RELATIONSHIPS AND LINKAGES
Link the requirements in the question with the keywords listed above. You may use
arrows or a simple concept map to help you.
Egg stage
Four-stage
life cycle of
Larva stage
Includes
an insect
example
Pupa stage
Adult stage
The pupa does not
feed or drink in
this stage
butterfly / housefly
/ ladybird beetle
Answers:
(a) Give an example of an insect that Karine could have kept in her tank.
Butterfly / housefly / ladybird beetle (any one)
___________________________________________________________________
(b) Explain your answer in part (a).
___________________________________________________________________
The butterfly / housefly / ladybird beetle undergoes a
four-stage life cycle which includes a pupa stage. The
___________________________________________________________________
insect does not feed or drink during the pupa stage.
___________________________________________________________________
-5-
PSLB | Cycles | Practice 2
© JustEdu Holdings Pte Ltd
At the end of each topic,
students are equipped with
a concept map and a list of
keywords and phrases to
reinforce the key concepts
of the topic.
Primary Lower Block | Cycles: Life Cycles | Concept Map
Life Cycles
A pattern that repeats itself to show the stages of development of a living thing
Flowering Plants
Animals
3 stages
3 stages
4 stages
Chicken
Butterfly
Cockroach
Housefly
Grasshopper
Mosquito
Egg
Egg
Seed
Adult
plant
Young
plant
Larva
Adult
Adult
Tomatoes
Young
Pupa
PSLB | Cycles | Concept Map (for student’s reference only)
-1-
© JustEdu Holdings Pte Ltd
List of Keywords and phrases

growth

incubation

larva

nymph

outer covering of an animal is replaced through the process of moulting

pupa

reproduction

seed leaves

vegetative propagation

warmth, oxygen and water are needed for germination
-2-
PSLB | Cycles | Concept Map (for student’s reference only)
© JustEdu Holdings Pte Ltd