Life cycles

1) What Is a Life Cycle?

● All living organisms, including plants, animals, fungi,

and bacteria, experience transformations as they
progress through their existence.
● The life of a living entity consists of various phases:
birth, growth, development, and reproduction,
collectively forming its life cycle.
● When living entities reach adulthood, they gain the
ability to reproduce. Their offspring will undergo the
same life stages as their parents. This perpetuates
the cycle.
● The life cycle plays a vital role in securing the
survival and continuity of living organisms.
● Even after the parents die, the young will live, grow, reproduce and become
adults.

2) How Are Life Cycles Similar or Different?

● Various animals undergo distinct stages of growth and development. Some living
organisms have more stages in their life cycles than others.
● The offspring of animals can either closely resemble their parents or exhibit
significant differences in appearance.
● Example:
- A kitten closely resembles an adult cat, while a tadpole looks quite
different from an adult frog.
● It's essential to understand that different animals possess varying life cycles,
which can differ in their duration. For example
- A fruit fly's life cycle is relatively short, spanning only a few weeks, while a
tortoise's life cycle is extended, lasting more than 20 years.
➢ Life Cycle of A Human
- The life cycle of a human consists of three stages.
➢ Life Cycle of A Chicken
➢ Life Cycle of A Frog
- Life cycle of a frog consists of three stages.
➢ Life Cycle of A Cockroach
- Life cycle of a cockroach consists of three stages.
➢ Life Cycle of A Butterfly
- Life cycle of a butterfly consists of four stages.
 ➢ Summary

Number of The Life Cycle Examples

Stages

Three Egg→Young→Adult Mammals:

- cat, cow, dolphin, elephant,rabbit
Live-bearing fish:
- guppy, swordtail
Birds:
- chicken, crow, parrot
Fish:
- clownfish, goldfish
Reptiles:
- crocodile, lizard, snake

Egg→Tadpole→Adult - Frog
- Toad

Egg→Nymph→Adult - Cockroach
- Damselfly
- Dragonfly
- Grasshopper

Four Egg→Larva→Pupa→Adult - Butterfly

- Mosquito
- Beetle
- Moth
- Housefly
3) The Life Cycle of Most Plants

● The life cycle of most flowering plants typically

involves three stages: seed, young plant, and
adult plant.
● This cycle begins with the seed and
progresses to the growth of a young plant,
eventually maturing into an adult plant
 My Revision Checklist

No. Points Yes No Unsure

1) I know what a life cycle is and

why it's important for living
things.

2) I can explain how different

living things have similar and
different life cycles.

3) I can talk about the different

stages in various animals’ life
cycles.

4) I can describe the stages in the

life cycle of plants that grow
from seeds.
 Class Exercise
Life Cycle of Plants

Section A
You will find four options for each question. Among these options, one is the correct
answer. Please indicate your choice (1, 2, 3, or 4) and record your answers within the
provided brackets.

1) Jeremy conducted an experiment using 4 identical jars with equal amounts of air
as shown below. He placed Jars B, C and D near the window while Jar A was
placed in the refrigerator.

In which of the jars, A, B, C, or D, will the seeds have the best conditions for
germination and development into seedlings?

(1) A
(2) B
(3) C
(4) D
2) Jenny wants to investigate how various soil types might impact the growth of tomato
plant seeds. What should she ensure remains consistent to obtain reliable results?

A The type of pot

B The type of soil
C The amount of soil
D The location of pot

(1) C only
(2) A and B only
(3) B and D only
(4) A, B, C and D
3) Emma arranged a hydroponics kit, as depicted below, and inserted a single seed into
each of the three cups. She stored her hydroponics kit in a dim closet for 9 days. Upon
inspection after 9 days, she noticed that the seeds had started to sprout, and their roots
were growing toward the water.

Day 1 Day 9

What allowed the seeds to sprout in the absence of light?

(1) They had air to facilitate germination.

(2) They had water to facilitate germination.
(3) They had warmth to facilitate germination.
(4) They had air, water, and warmth to facilitate germination.
4) The diagrams below show the life cycle of a plant that is in an incorrect sequence.

A B C D

Rearrange the sequence in the correct order and choose one of the following.

(1) B→A→D→C
(2) B→A→C→D
(3) A→C→B→D
(4) D→A→C→B

5) A student purchased two identical pots of daisy plants for an experiment. Each day,
they provided both pots with 300ml of water, but they added 10 ml of fertilizer to only
one of the pots. Over the following 9 days, the student monitored and documented the
growth of the daisy plants every other day.

What was the pupil attempting to determine with this experiment?

(1) The maximum height the plant could reach.
(2) The plant's water requirements.
(3) The plant's fertilizer requirements.
(4) Whether the plant's height increased when fertilizer was applied.
6) What are the four main parts of a plant?

(1) Root, stem, leaves, flowers

(2) Root, stem, leaves, fruits
(3) Root, stem, leaves, seeds
(4) All of the above

7) How do plants reproduce?

(1) Plants reproduce by pollination and fertilization.

(2) Plants reproduce by seeds.
(3) Plants reproduce by spores.
(4) All of the above
Section B
Carefully read each question and fill in the answers in the provided spaces.

1) Andy planted five pots of bean seedlings. He positioned them on the balcony and
provided daily watering with varying amounts of water. After a span of two weeks,
he gauged the height of the seedlings and documented the outcomes in a chart.
Review his chart below.

a) What was Andy aiming to find out from the experiment? [1]

b) From which pot was the seedling the tallest after 2 weeks? Explain why. [1]
2) In an experiment, Sarah positioned an equal number of green bean seeds on moist
cotton wool in three dishes. Subsequently, she situated each dish in a container.
Container X had an opening on the top. Container Y had an opening on one side, and
Container Z had no opening, as depicted in the diagram below. After several days,
Sarah observed that all the seeds had germinated.

Container X Container Y Container Z

a) Name the conditions that allowed the seeds to germinate. [1]

b) Sarah then took the dishes out of the containers. The diagrams provided below
show her observations. Write the letters A, B, or C inside the suitable boxes
beneath each diagram to indicate the container in which the green beans had
been positioned.
 Class Exercise
Life Cycle of Animals

Section A
You will find four options for each question. Among these options, one is the correct
answer. Please indicate your choice (1, 2, 3, or 4) and record your answers within the
provided brackets.

1) The diagram below shows the life cycle of an animal.

Which of the following animals is likely to possess the life cycle depicted above?
(1) Beetle
(2) Butterfly
(3) Housefly
(4) Grasshopper
 2) The life cycles of two animals are shown below.

Life cycle A Life cycle B

Based on the information provided, which of the following statements is accurate?

(1)Both adult animals X and Y are egg layers.

(2)Animal Y's life cycle consists of more stages than Animal X.
(3)The offspring of both animals X and Y share similarities with their parents.
(4)In the adult stage, Animal X possesses wings, while Animal Y lacks wings.

3) The picture below shows the larva of a butterfly that was moulting.
Which of the following explains why moulting is necessary?

(1) It has outgrown its old outer covering.

(2) It increases its chances of reproduction.
(3) It needs to change from a pupa to a larva.
(4)It needs to eat its old outer covering for food.

4) A mosquito’s life cycle is shown in the diagram below.

At which stage of its life cycle is the mosquito harmful to humans?

(1) Egg
(2) Larva
(3) Pupa
(4) Adult
5) Three students, Alex, Mia, and Max, made the following statements about a
cockroach and a beetle.

Alex: Their offspring lack wings.

Mia: Their young resemble the adults.
Max: They go through four stages in their life cycles.

Which of the students is/are correct?

(1) Alex only
(2) Mia only
(3) Mia and Max
(4) Alex and Max

6) The diagram below depicts the life cycles of four different insects. Considering the
information provided in the diagrams, which of these insects is expected to pose the
greatest threat to cotton plants?
 7) Study the flowchart below.

What could animals X, Y and Z be?

Option Animal X Animal Y Animal Z

(1) Dragonfly Toad Mosquito

(2) Cockroach Dragonfly Frog

(3) Butterfly Duck Dragonfly

(4) Mosquito Frog Chicken

8) The number of days in each stage of the life cycle of insect A and insect B is shown
in the graph below.

At what stages would Insects A and B be on the 17th day after their eggs were laid,
respectively?

Option Insect A Insect B

(1) Pupa Pupa

(2) Pupa Larva

(3) Larva Larva

(4) Larva Pupa

9) A flow chart is given below.

Which animal/insect could X, Y and Z be?

X Y Z

(1) Hen Cockroach Mealworm

(2) Mealworm Man Hen

(3) Mealworm Cockroach Man

(4) Cockroach Hen Mealworm

Section B
Carefully read each question and fill in the answers in the provided spaces.

1) Durga drew a flow chart below.

a) Upon studying the flow chart above, Describe Animal X. [1]

b) One of the animals above has been classified wrongly, identify that animal. Explain how
you managed to identify. [1]

c) State one difference between the lion and the chicken from the flow chart above. [1]
2) The length of each stage in the life cycles of Insect X and Insect Y is shown in the graphs
below.

a) Upon studying the graphs, state one similarity in the life cycles between insect X and
Insect Y. [1]

b) Upon studying the graphs, state one difference in the life cycles between insect X and
Insect Y. [1]

c) Upon studying the graphs, which insect, after hatching from its egg, takes a longer time
to develop into an adult? Explain your answer. [2]