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Science - Grade 7
Self-Learning Module
Quarter 2 – Module 4 – Heredity: Inheritance and Variation
Second Edition, 2021
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This module was designed and written with you in mind. It is here to help you
differentiate asexual from sexual reproduction in terms of number of individuals
involved and similarities of offspring to parents. The scope of this module allows
you to use it in many different learning situations. The language used recognizes the
diverse vocabulary level of students. The lessons are arranged to follow the standard
sequence of the course. But the order in which you read them can be changed to
correspond with the textbook you are now using.
This module is composed of two lessons:
• Lesson 1 – Sexual Reproduction
• Lesson 2 - Comparison between Asexual and Sexual Reproduction
After going through this module, you are expected to
1. describe sexual reproduction,
2. explain how fertilization takes place,
3. describe conjugation,
4. identify the reproductive structures of al flowering plant (gumamela),
5. describe the function of each structure of a flowering plant in
reproduction,
6. differentiate asexual from sexual reproduction.
Sexual reproduction is a mode of reproduction that involves two parents. The
parents produce reproductive cells called gametes through a type of cell division
called meiosis. Meiosis will be discussed in detail in Grade 8.
Organisms reproduce sexually in several ways. Let us look at the different ways
how some microorganisms, plants, animals, and humans reproduce sexually.
Lesson
1 Sexual Reproduction
I Need to Know
Lesson Overview
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Sexual Reproduction in Microorganisms
Conjugation is the process by which a microorganism transfers genetic
material to another through direct contact. An example of a microorganism that
reproduces by conjugation is Spirogyra, a green alga. Spirogyra can be found in
freshwater habitats such as ponds and rivers. During conjugation, a bridge forms
between two cells of two Spirogyra filaments lying side by side. The contents of
one cell pass into the other cell through the bridge, emptying the other cell. The
contents of both cells combine in the other cell and form the zygote. This zygote
can secrete a substance that forms a wall around itself for protection against
unfavorable environmental conditions (ex. when the pond dries up). When
conditions become suitable for growth and development, the zygote grows into a
new individual.
Figure1. Spirogyra (green algae)
Sexual Reproduction in Flowering Plants
The flower is the reproductive organ in flowering plants. Flowers have
structures that produce the gametes necessary for reproduction. Let us take a look
at the reproductive parts of a gumamela flower.
The transfer of pollen grains from the anther of one flower to the stigma of the
same or another flower is known as Pollination.
Figure 2. Reproductive Structures of a Gumamela flower
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Parts of the
Flower
Description Function
Stamens male reproductive organ of a flower.
• consists of the filament and the anther
• produce pollen grains
Filament • a long cylindrical tendril part of the stamen. • hold up the anther in position
tall enough to release the
pollen.
Anther • consists of pollen sacs.
• pollen sacs contain pollen grains that
contains male reproductive cells
• produces pollen grains
• releases when they mature.
Pistil or
carpel
• a female reproductive organ of a flower
• round shaped located in the flower’s center
• consists of stigma, style, and ovary.
• produces ovules (Ovule is the
organ that forms the seeds of
flowering plants.)
Stigma • a sticky and has hair-like structure located
on topmost part of the pistil
• captures the pollen grains
transported to the stigma of
the flowers by wind or
pollinators
Style • joins the ovary to the stigma. • passageway to transport
pollen grains to the ovary.
Ovary • located at the base of the pistil where the
ovules are produced
• ovule is the part where female reproductive
cells of the plant are produced and
contained.
• produces and contains
unfertilized seeds or ovules
Receptacle • enlarged upper end of a flower stalk • connects the stalk to the
flower and provide support
Sepals • small, green, leaf-like structures located at
the base of a flower.
• protect the flower bud.
Petals • highly colored portions of a flower. • attract or draws pollinators
such as bees to the flower.
Sexual Reproduction in Humans and Animals
Humans and all animals that reproduce sexually have sex cells called gametes.
In males, testes produce sperm while female ovaries produce egg (ova). When
conditions are right, sperm and egg unite in a process known as fertilization. The
resulting fertilized egg or zygote will have a unique combination of genes from both
parents.
Figure 3. Fertilization in Humans
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Activity 1A: Conjugation Process in Spirogyra
Study the illustration of the conjugating spirogyra below then perform the activity.
Place all your answers for the activity on a separate answer sheet.
Figure 4. Spirogyra conjugating
Materials
Cut- outs Bond Paper Scissors
Marking pen/ ballpen Paste
Procedure
1. Read the lesson overview about conjugation.
2. Cut out each picture below and paste it in a correct sequence to show the
step-by-step process of conjugation in spirogyra. Please stipulate the step-
by-step process in lesson overview.
I Will Do This
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Activity 1B: The Pollination Process
Material(s)
Activity sheet, ballpen
Procedure
1. Read the lesson overview about sexual reproduction in flowering plants.
2. Arrange the steps of pollination in the correct order by writing them in the
boxes provided on the illustration below. Select your answer from the box.
• As the bee drinks more nectar in this new flower, the pollen on its body rubs
off to the female parts of the second flower (the stigma).
• The brightly colored petals and the scent of the flower attract the bee.
• Part of this pollen travels down the style and then into the ovary.
• The bee arrives on the flower to collect nectar.
• As the bee collects the nectar, pollen brushes onto its legs and body.
• After the bee is done feeding on the flower’s nectar, it gets hungry and gets
attracted by another flower’s bright colors.
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Analysis Questions:
Check the box of the correct answer.
1. How is conjugation in spirogyra accomplished?
Two filaments of Spirogyra form conjugation tubes. The male gametes fuse with
female gametes to form zygotes.
Two filaments of Spirogyra come side by side. The male gametes stay close to
the female gametes to form zygotes.
2. How does pollination occur in flowering plants?
Pollination process occurs when pollen grains from the female part of one
flower (stigma) are transferred to the male part (anther) of another flower.
Pollination process occurs when pollen grains from the male part of one
flower (anther) are transferred to the female part (stigma) of another flower.
Listed below are the processes that occur during sexual reproduction in
microorganisms (spirogyra), flowering plants and humans. Select the correct process
from the word box for each by filling in the empty boxes below them.
I Will Practice
FERTILIZATION
CONJUGATION
POLLINATION
MICRORGANISMS
(SPIROGYRA)
FLOWERING
PLANTS
HUMANS AND
ANIMALS
SEXUAL REPRODUCTION
in
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Identify the pictures that show sexual reproduction in microorganisms, flowering
plants, and humans. Write √ if the picture shows sexual reproduction and X if not.
Place your answers in the answer sheet.
Lesson
2
Comparison between
Asexual and Sexual
Reproduction
There are two basic types of reproduction: asexual reproduction and sexual
reproduction. Asexual reproduction involves a single parent. It results in offspring
that are genetically identical to each other and to the parent. All prokaryotes and
some eukaryotes reproduce this way. There are several methods of asexual
reproduction. They include binary fission, fragmentation, vegetative propagation and
budding. Asexual reproduction can be very rapid. This is an advantage for many
organisms. It allows them to crowd out other organisms that reproduce more slowly.
Bacteria, for example, may divide several times per hour. Under ideal conditions,
100 bacteria can divide to produce millions of bacterial cells in just a few hours.
I Will Apply
Lesson Overview
1. 2. 3.
4. 5.
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However, most bacteria do not live under ideal conditions. If they did, the entire
surface of the planet would soon be covered with them. Instead, their reproduction is
kept in check by limited resources, predators, and their own wastes. This is true of
most other organisms as well. Sexual reproduction involves two parents and
produces offspring that are genetically unique. Methods of sexual reproduction
include conjugation (in some microorganisms), pollination (in flowering plants) and
fertilization (in human and most animals).
Methods of Reproduction Comparison Chart
Characteristics Sexual Asexual
Definition Reproduction that involves
the union of sex cells or
gametes
Reproduction that does
not involve sex cells or
gametes
Number of parents Two parent organisms (male
and female)
A single parent organism
or cell
Cell multiplication By meiosis By mitosis
Rate of producing
offspring
Slow; produces at least one
offspring
Quick, produces several
offspring
Variations in appearance Offspring with resemblance to
parents but not identical to
them
Appearance of offspring is
identical to parent
Advantages Result in variations among
offspring that help them live
longer and survive
No mate needed; requires
less energy
Disadvantages Requires both sexes to
participate
Requires more energy
Very little chance of
genetic variation
Activity 1: Sexual Vs. Asexual Reproduction:
A Venn Diagram
Materials
Worksheet Bond Paper Marking pen
I Will Do This
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Procedure
1. Read the lesson overview regarding comparison between asexual and
sexual reproduction.
2. Based on data gathered from the readings, using the words listed in the box,
complete the Venn Diagram to illustrate the similarities and differences in
sexual and asexual reproduction using the worksheet provided.
Analysis Questions:
Check the box of the correct answer.
1. Compare sexual and asexual reproduction. How do they differ in terms of
the number of individuals involved?
Sexual reproduction involves two parents while asexual reproduction involves
a single parent.
1. One parent
2. Forms of reproduction
3. Creates a minimum of 1 offspring
4. Found in higher/complex organisms
5. Produces offspring
6. Cells divide by mitosis
7. No formation of gametes
8. Formation of gametes
9. Involves plants, fungi, & animals
10.Genetic variation in offspring
11.Very little chance of genetic variation
12.Cells divide by meiosis
13.Two parents
14.Found in lower organisms
15.Generally, creates a minimum of two offspring
Sexual Reproduction Asexual Reproduction
Characteristics
present in both
sexual & asexual
reproduction
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Sexual reproduction involves a single parent while asexual reproduction
involved two parents.
2. How do they differ in terms of their offspring?
In asexual reproduction, the offspring will have a unique combination of traits
while in sexual reproduction, the offspring will show a genetic make-up that is
identical to the parent.
In asexual reproduction, the offspring will show a genetic make-up that is
identical to the parent while in sexual reproduction, the offspring will have a
unique combination of traits
3. What are the advantages of each type of reproduction?
Sexual reproduction results in variations among offspring that help them live
longer and survive. Asexual reproduction does not require a mate and it
requires less energy.
Asexual reproduction results in variations among offspring that help them live
longer and survive. Sexual reproduction does not require a mate and it requires
less energy.
List down the methods of Sexual and Asexual Reproduction on the table
below.
Methods of Sexual and Asexual Reproduction
Sexual Reproduction Asexual Reproduction
I Will Practice
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Identify the organisms that were sexually and asexually reproduced. Write SR
if the organism was Sexually Reproduced and AR if it was Asexually Reproduced on
the box provided for each number.
References
Books:
Learner’s Module pages 112 -121
Internet:
https://www.toppr.com/guides/biology/sexual-reproductio-in-flowering-plants/sexual-
reproduction
https://apopkascience.weebly.com
https://peda.net/kenya/css/subjects/biology/form-three/ripaa
I Will Apply
1. 2.
4.
3.
5. 6.
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Module 4 - Heredity: Inheritance and Variation
Lesson 1: Sexual Reproduction
I Will Do This
Activity 1A: Conjugation Process in Spirogyra
Activity 2B: The Pollination Process
Step 1 - The brightly coloured petals and the scent of the flower
attract the bee.
Step 2 - The bee arrives on the flower to collect nectar.
Step 3 - As the bee collects the nectar, pollen brushes onto its legs
and body.
Step 4 - After the bee is done feeding on the flower’s nectar, it gets
hungry and gets attracted by another flower’s bright colors.
Step 5 - As the bee drinks more nectar in this new flower, the pollen
on its body rubs off to the female parts of the second flower ( the
stigma).
Step 6 - Part of this pollen travels down the style and then into the
ovary.
Analysis Questions
1.How is conjugation in spirogyra accomplished?
Two filaments of Spirogyra form conjugation tubes. The male
gametes fuse with female gametes to form zygotes.
2.How does pollination occur in flowering plants?
Pollination process occurs when pollen grains from the male part of
one flower (anther) are transferred to the female part (stigma) of
another flower.
I Apply This
1. X
2. √
3. √
4. X
5. √
Answer Key
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Lesson 2: Comparison between Asexual
and Sexual Reproduction
I Will Do This
Analysis Questions
1. Compare sexual and asexual reproduction. How do they differ in
terms of the number of individuals involved?
Sexual reproduction involves two parents while asexual reproduction involves
a single parent.
2. How do they differ in terms of their offspring?
In asexual reproduction, the offspring will show a genetic make-up that is
identical to the parent while in sexual reproduction, the offspring will have a
unique combination of traits.
3. What are the advantages of each type of reproduction?
Sexual reproduction results in variations among offspring that help them live
longer and survive. Asexual reproduction does not require a mate and it requires
less energy.
I Will Practice
Sexual Reproduction
1. Conjugation
2. Pollination
3. Fertilization
Asexual Reproduction
1. Binary fission
2. Budding
3. Fragmentation
4. Regeneration
5. Vegetative
propagation
6. Spore formation
I Will Apply
1. AR
2. SR
3. AR
4. SR
5. AR
6. SR
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Name: _______________________________ Grade & Section: ___________
Part I. Multiple Choice. Read each item carefully. Select the letter of the best answer
1. An egg cell unites with a sperm cell to form a zygote. Which process is taking
place?
A. fertilization
B. fragmentation
C. pollination
D. vegetative propagation
2. The offspring from asexually reproduced organisms are?
A. different than their parents
B. identical to parents
C. a combination from both parents
D. a different species
3. A farmer grew only one type of corn. All the corn plants died from the
same disease. What can be said of this corn plant population?
A. The corn plants were genetically identical.
B. Only a few plants were resistant to the disease.
C. All the corn plants were resistant to the disease.
D. The corn plants were genetically different from each other.
4. Which species can produce offspring that are genetically different from
their parents?
A. A species that has few variations.
B. A species that reproduces sexually.
C. A species that reproduces asexually.
D. A species that competes with a similar species.
5. Complete the following sentence: Pollination is the transfer of a pollen
process from__________.
A. the anther to the stigma
B. the stigma to the anther
C. the stigma to the ovary
D. the ovary to the stigma
Written Assessment No. 4 Worksheet
Concept Check
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6. Which of the following structures are not involved in asexual reproduction?
A. gametes
B. root
C. stem
D. tuber
7. Which of the following performs fertilization during reproduction?
A. chicken
B. hydra
C. mushroom
D. yeast
8. Which of the following reproduces by regeneration?
A. crab
B. sponge
C. squid
D. starfish
9. A hydra reproduces when an outgrowth, or bud, forms and continues to
develop until if falls off the parent. This is an example of:
A. binary fission
B. spore formation
C. budding
D. vegetative propagation
10.Which of the following differentiates asexual from sexual reproduction?
A. Asexual reproduction requires gametes while sexual reproduction
requires body parts.
B. Asexual reproduction undergoes fertilization while sexual reproduction
undergoes binary fission.
C. Asexual reproduction does not require gametes while sexual
reproduction requires the union of body parts.
D. Asexual reproduction produces offspring which is different from the
parent while sexual reproduction produces offspring identical to the parent.
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Part II. Enumeration.
Some microorganisms, flowering plants, animals, and humans reproduce sexually.
The 3 methods of sexual reproduction are as follows:
METHODS OF SEXUAL
REPRODUCTION
DESCRIPTION EXAMPLE
Reflection Question:
What is the importance of reproduction, what will happen if reproduction would stop??
___________________________________________________________________
___________________________________________________________________
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I. Multiple Choice
1. A 6. A
2. B 7. A
3. A 8. D
4. B 9. C
5. A 10. C
II. Enumeration
Reflection
The importance of reproduction is to keep on increasing the species. If an
organism stops the "process of reproduction", there will be no "next
generation"
FOR TEACHER’S USE ONLY. Do not attach this portion to the SLM for students.
Answer Key to Concept
Check
