8
Science
Quarter 4 – Module 1
The Digestive System
Learner’s Activity Sheet
Photo Credit: https://www.google.com/search?sa=X%2Chemical+images+cartoon; May 24, 2021
Science – Grade 8
Activity Worksheet
Quarter 4 – Biology
First Edition, 2020
Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of
the Philippines. However, prior approval of the government agency or office wherein the work is created shall be
necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a
condition the payment of royalties.
Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included
in this book are owned by their respective copyright holders. Every effort has been exerted to locate and seek
permission to use these materials from their respective copyright owners. The publisher and authors do not
represent nor claim ownership over them.
THE DIGESTIVE SYSTEM
Food plays a central role in the survival of species. Food gives organisms energy that enables them to
carry out the many activities they do each day; this includes predators chasing a prey or prey escaping a predator,
arboreal organisms climbing trees to gather fruits, or fish swimming in schools in search for food, to name a few.
Organisms are able to obtain energy from the foods they eat through digestion.
Digestion of food is carried out by the organs and substances of the digestive system. During digestion,
food is broken down to smaller parts -- a fraction of which is made up of nutrients. These nutrients are circulated
to the different parts of the body through the bloodstream and assimilated by cells.
Almost all animals have a digestive system in which food enters the mouth, is moved through a long tube,
and exits the anus as feces. The food is broken down into soluble molecules and is moved rhythmically by the
smooth muscle in the walls of the digestive organs.
Different species of organisms have different ways of digesting their food. In humans, digestion starts in
the mouth where food is chewed and broken down to smaller pieces for easier digestion. This is called mechanical
digestion. Initial chemical digestion starts also in the mouth. This is carried out by enzymes -- molecules that
speed up chemical reactions. Enzymes present in saliva such as amylase helps break down carbohydrates, which
are large complex molecules, into simpler ones that can be used by the body.
After swallowing, the food -- now turned into a bolus -- enters the esophagus (gullet) and is moved down
into the stomach where it mixes with gastric juices and acids. Other enzymes such as protease and lipase help
break down proteins in the stomach and fats in the small intestine, respectively. Digestion ends in the small
intestine where nutrients are absorbed in the villi and enter the circulatory system. Wastes that remain after
digestion go to the large intestine where water is also reabsorbed. These wastes, including the water that was not
reabsorbed, are temporarily stored in the rectum before they are excreted out of the body through the anus.
Digestion in other organisms works similarly. However, there are specialized structures found in some
species that perform special digestive functions. This module introduces you to the different organs that make up
the digestive system of animals and how they interact with each other to digest food and nourish their bodies.
Emphasis is given on the human digestive system and its processes.
MODULE 1 – THE DIGESTIVE SYSTEM
OVERVIEW
The digestive systems of animals and the organs that make them up vary
across species. Some structures like the rumen, crop, and gizzard are found only in
some species. The rumen is common among ruminants that include the goats, cows,
and carabaos. What do you think is the function of this structure? The crop and
gizzard are found in birds and some species of invertebrates like the grasshoppers
and earthworms. What functions do you think do these structures perform in
digestion?
Almost all animals have a tubelike digestive system; one end of the tube
serves as the mouth while the other end serves as the anus. This digestive system is
called a Complete Digestive System. Food enters the mouth, passes through the
long tube, and exits as feces through the anus. The smooth muscles of the tubelike
digestive organs move the food rhythmically through the system where it is broken
down into absorbable forms. Outside of this tube are attached some accessory
organs -- the liver, gall bladder, and pancreas -- which also help in the digestion of
food. Figure 2 shows a comparison of the digestive systems of different representative
species of animals.
Figure 1. The human digestive
system
The more primitive animals like the Hydra have a
‘digestive system’ with only one opening (see Figure 3)
which is also called an Incomplete Digestive System.
These organisms eat and defecate with their mouth which
also alternates as their anus!
Figure 2. Digestive systems of different representative species of animals.
Figure 3. (a) Hollow body of Hydra. The animal takes in food, digests
food in its digestive cavity, and removes wastes through its mouth, (b)
is an enlarged part of the body wall, and (c) the outer part of the wall
shows the nematocysts.
LET’S TRY! (PRE-ASSESSMENT)
Digestive Word Search: LOCATE AND BOX THE WORDS/TERMS
related to the Digestive System using the clues given below. (IT COULD BE HORIZONTAL, VERTICAL, DIAGONAL TO
THE LEFT OR DIAGONAL TO THE RIGHT.)
.
Clue 1 - An enzyme found in the mouth that breaks down starch.
Clue 2 - The movement of food through the digestive system.
Clue 3 - Breaks down proteins into shorter polypeptide chains.
Clue 4 - Increases the surface area for absorbing broken down food products in the small intestine.
Clue 5 - The organ in charge of making insulin.
Clue 6 - A liquid that digests large fat particles.
Clue 7 - Caused due to the presence of additional water in the intestines. The feces can become very watery.
Clue 8 - Small cholesterol deposits that form in the gallbladder. When gallstones can be secreted into the bile duct. When
this happens, they block the flow of bile causing severe pain.
Clue 9 - Small pores or openings in the lining of the stomach. Caused due to the presence of excessive acid or bacteria in
the stomach.
CONTENT STANDARD
The learners demonstrate understanding of the digestive system and its interaction with the circulator,
respiratory, and excretory systems in providing the body with nutrients for energy.
PERFORMANCE STANDARD
The learners should be able to present analysis of the data gathered on diseases resulting from nutrient
deficiency.
MOST ESSENTIAL LEARNING COMPETENCY
Explain ingestion, absorption, assimilation, and excretion. S8LTIVa-13
E. Science 8
FOURTH QUARTER WEEK 1: Written Work No. 1
For the learner:
This worksheet contains activities about the organs and its functions involved in Digestive system. You
may answer directly to this activity sheets and make sure to follow the directions stated in each part of the
activity. Answer all questions the best that you can and please write legibly.
For the parents:
Learners may require your guidance in following the directions and answering the questions in each part
of the activity. Make sure that they answer each part of the worksheet.
Objectives:
 Identify the principal components of the digestive system.
 Describe the function of each structure involved in the digestive system.
WEEK 1: DAY 1 - ACTIVITY #1 – THE DIGESTIVE SYSTEM
WHAT I NEED (MATERIALS)
 Worksheet
 Pen
 Coloring materials
WHAT TO DO (PROCEDURE)
Describe the function of each structure involved in the digestive system in the table below. Use the
information from the table to label and color the diagram.
Note: Start making a record of your daily food intake from this day (Monday) until the fifth day of the week.
Here is the format:
Date
Breakfast
Daily Record of Food Intake
AM Snacks
Lunch
PM Snacks
Dinner
Remarks
WHAT I LEARNED (GENERALIZATION)
Write down in the box what you have learned from the lesson.
WHAT I CAN DO ABOUT IT (APPLICATION)
Scenario Building: (Optional: You may also do dramatization): What will happen to body functions
if the following organs will not perform well?
1. Teeth
2. Large Intestine
3. Pancreas
4. Stomach
5. Tongue
CHALLENGE (EVALUATION)
Multiple Choice: Circle the CORRECT answer.
1. The major functions of the digestive system are to digest food and to absorb nutrients into the
__________.
a. stomach
b. small intestine
c. bloodstream
2. Which of the following is considered to be an accessory organ of digestion?
a. pancreas
b. stomach
c. small intestine
3. Secretion is an important process of digestion. Which of the following best describes one concept
of secretion in reference to the digestive system?
a. Secretion is the movement of food through the gastrointestinal tract.
b. Secretion is the release of waste products from the action of digestion.
c. Secretion is the release of digestive enzymes from various organs to digest food.
4. Which of the following is the term that refers to the movement of food through the digestive
system via the action of smooth muscles?
a. Peristalsis
b. ingestion
c. defecation
5. Food is broken down in the mouth both mechanically by chewing, and chemically, by ____
present in the saliva.
a. urine
b. enzymes
c. amino acids
E. Science 8
FOURTH QUARTER WEEK 1: Performance Task No. 1
For the learner:
This worksheet contains activities about the organs and its functions involved in Digestive system. You
may answer directly to this activity sheets and make sure to follow the directions stated in each part of the
activity. Answer all questions the best that you can and please write legibly.
For the parents:
Learners may require your guidance in following the directions and answering the questions in each part
of the activity. Make sure that they answer each part of the worksheet.
Objectives:
 describe how mechanical and chemical digestion happen and how chemical and physical
breakdown of food help in digestion;
 identify where these types of digestion occur;
 explain the action of enzymes as catalysts, and how it helps in digestion
 demonstrate how absorption and excretion happen.
Two types of Digestion:
1. Mechanical Digestion – the physical breakdown of food into smaller pieces
Where it happens: mouth through the help of the teeth by chewing.
2. Chemical Digestion – the breaking down of food into simpler nutrients that can be readily absorbed by the cells
of the body.
Where it happens: mouth through the help of the saliva, stomach and small intestines using enzymes
WEEK 1: DAY 2 - ACTIVITY 2.1 – DIGEST ME UP!
WHAT I NEED (MATERIALS)




Worksheet
Pen
Crackers
Vinegar




Plastic cup
Bread
Ziploc bag/plastic bag
strainer
WHAT TO DO (PROCEDURE)
Pre-lab: Direction: Arrange the following processes according to the correct sequence of events of digestion:
Mechanical Digestion – Excretion – Absorption – Chemical Digestion - Ingestion
Answer: __________________________________________________________________________
Note: Make a photo documentation while conducting the activity (before, during and after).
Part A:
1.
2.
3.
4.
Get a piece of cracker and taste it. Eventually, chew the crackers. Record its taste and texture.
Get another piece of cracker and let it sit inside your mouth for 1.5 minutes.
Then, chew the cracker. Observe its texture and compare it to the first cracker you chewed.
Refer to the questions below for your observations.
Part B:
1.
2.
3.
4.
Tear bread into small pieces and place it inside the Ziploc bag.
Pour small amount of vinegar inside the bag.
Close the bag and squish it. Be careful not to spill the content of the bag.
Observe the result.
ANALYSIS:
PART A
1. How is the initial taste of the cracker? How about the second cracker?
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
2. Describe the texture of the bread after one minute inside your mouth. How does it feel?
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
3. Which type of digestion happened in this setup? Explain.
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
4. Which organ do you think is such type of digestion happening?
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
PART B
1. What happened to the bread inside the bag after putting vinegar on it?
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
2. Which type of digestion happened in this setup? Explain.
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
3. Which organ do you think is such type of digestion happening?
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
WHAT I CAN DO ABOUT IT (APPLICATION)
Compare and Contrast the two types of digestion using double bubble map (graphic organizer).
Rubrics:
5- if all information are correct;
4- if one instance of incorrect information;
3 – 2-3 instance of incorrect information
2- only one information is correct;
1- non-submission
Graphic Organizer:
CHALLENGE (EVALUATION)
Determine whether the event is mechanical or chemical digestion:
1.
2.
3.
4.
5.
Chewing of food - _____________________________
Churning of food - _____________________________
Bolus formation - ______________________________
chyme formation - _____________________________
use of enzymes for digestion - ____________________
WEEK 1: DAY 2 - ACTIVITY 2.1 – DIGEST ME UP!
Overview:
What are enzymes?
Enzymes are biological catalysts – they speed up the chemical reactions that take place inside all cells, but without
being used up in the process. There are many thousands of different types of enzymes, and each one catalyzes a different
reaction. Cells create enzymes based on instructions carried in the cell’s genes (DNA).
What are enzymes made of?
Enzymes are protein molecules, and so are made up of amino acids. Most enzymes contain between 100 and 1,000
amino acids. These amino acids are joined together in a long chain, which is folded to produce a unique 3D structure.
Different types of enzymes have different shapes and functions because the sequence and type of amino acids in their
structure is different.
Why are enzymes so specific?
Enzymes are very specific about which reactions they catalyze. Only molecules with exactly the right shape will
bind to the enzyme and react. These are the reactant, or substrate, molecules. The part of the enzyme to which the reactant
binds (attaches) is called the active site. This is a very specific shape and the most important part of the enzyme.
WHAT I NEED (MATERIALS)
 Worksheet
 Pen
WHAT TO DO (PROCEDURE)
Part 1: Fill in the gaps in the following sentences using the words in the box below.
different
catalysts
function
the same
amino acids
catalysts
1. Enzymes are biological __________________ that speed up chemical reactions in living organisms.
2. Enzymes are protein molecules, which are made up of long chains of _________________.
3. The sequence and type of amino acids are _____________ in each protein, so they produce enzymes with many
different shapes and functions.
4. The shape of an enzyme is very important to its ___________________.
Write down the name of the nutrient next to the enzyme that breaks it down. Use the words in the box below.
*Use device to look up if needed.
fats
sucrose
starch
proteins
carbohydrates
hydrochloric acid
a. Carbohydrase is an enzyme that breaks down _______________
b. Protease is an enzyme that breaks down _______________
c. Lipase is an enzyme that breaks down _______________
d. Amylase is an enzyme that breaks down _______________
Infer: Lactase is an enzyme that helps your body break down milk sugars called lactose. A person who does not
produce enough lactase eats a bowl of ice cream. What do you think will be the effect on the person?
___________________________________________________________________________________________
Infer: Lactose is found in milk products. It is converted by the body into a usable form in a series of chemical
reactions. The diagram shows the series of reactions that convert lactose into a usable form.
If enzyme 2 is denatured (destroyed), the levels of which substance will increase? ____________________
Part 2: Label the image with the following terms: active site, reactant, enzyme.
WHAT I LEARNED (GENERALIZATION)
Write down in the box what you have learned from the lesson.
E. Science 8
FOURTH QUARTER WEEK 1: Performance Task No. 2
For the learner:
This worksheet contains activities about the organs and its functions involved in Digestive system. You
may answer directly to this activity sheets and make sure to follow the directions stated in each part of the
activity. Answer all questions the best that you can and please write legibly.
For the parents:
Learners may require your guidance in following the directions and answering the questions in each part
of the activity. Make sure that they answer each part of the worksheet.
Objectives:
 identify essential nutrients needed by the body and where to get it.
 visualize how much nutrients the body needs.
 recognize the importance of eating nutritious food.
Nutrients
Carbohydrates
Proteins
Fats
Vitamins
Six Important Nutrients Needed by the Body
Effect on the Body
Food Sources
serve as the main energy source for the
Fruits, breads and grains, starchy
brain
vegetables, sugars
build and repair body tissues
Low-fat meat, dairy, beans. eggs
Fish, walnuts vegetable-based oils,
increase absorption of fat-soluble vitamins
seeds, avocado
like Vitamin A, D, E and K
Vitamin C
synthesizes collagen
Citrus fruits, strawberries, peppers
Folate (Vitamin B)
helps prevent birth defects
Dark green leafy vegetables, fruits,
poultry, meat, sea food and grains
Vitamin D
helps maintain calcium synthesis
Fatty fish (mackerel, salmon), beef
liver, cheese, egg yolk
Sodium
Celery, beets, milk
maintains fluid volume outside the cell and
helps cells function normally
Minerals
Potassium
maintains fluid inside the cell and prevents
excess rise in blood pressure
Bananas, potatoes and tomatoes
Calcium
helps maintain and builds strong bones and Milk, low-fat cheese, yogurt
teeth
Water
helps maintain homeostasis in the body
All beverages and high moisture
and transports nutrients to cells
food (soup, watermelon)
Assists in removing waste product
Source: http://healthyeating.sfgate.com/6-essential-nutrients-functions-4877.html
WEEK 1: DAY 3 - ACTIVITY 3.1 – WHAT’S ON YOUR PLATE?
WHAT I NEED (MATERIALS)
 Worksheet
 Pen
 Pictures of Pinggang Pinoy
WHAT TO DO (PROCEDURE)
Carefully observe the following illustrations/pictures and compare the different plates from
the different age group and answer the following Guide Questions.
Figure 1: Pinggang Pinoy for Kids
http://www.fnri.dost.gov.ph/images/sources/PinggangPinoy
-Kids.pdf
Figure 3: Pinggang Pinoy for Adults
http://www.fnri.dost.gov.ph/images/sources/PinggangPinoyAdult.pdf
Figure 2: Pinggang Pinoy for Teens
http://www.fnri.dost.gov.ph/images/sources/PinggangPinoyTeens.pdf
Figure 4: Pinggang Pinoy for Elderly
http://www.fnri.dost.gov.ph/images/sources/PinggangPinoyElderly.pdf
Figure 5: Pinggang Pinoy for Pregnant and Lactating Mothers
http://www.fnri.dost.gov.ph/images/sources/PinggangPinoyPregnant-and-Lactating-Women.pdf
Guide Questions:
1. What have you noticed with all the “Pinggang Pinoy” illustrations?
____________________________________________________________________________________________
____________________________________________________________________________________________
2. How are they the same? How are they different?
____________________________________________________________________________________________
____________________________________________________________________________________________
3. As a teenager, what have you noticed with the “Pinggang Pinoy” for your age group?
____________________________________________________________________________________________
____________________________________________________________________________________________
4. Why do you think so?
____________________________________________________________________________________________
____________________________________________________________________________________________
WEEK 1: DAY 3 - ACTIVITY 3.2 – BUILD ME UP!
WHAT I NEED (MATERIALS)




Worksheet
Pen, scissors and glue
Illustration of a teenager
Nutrient chips
WHAT TO DO (PROCEDURE)
Cut and paste the following nutrient chips on the body of the teenager.
Nutrient Chips:
Carbohy
drates
Protein
Water
Fats/
Oils
Fats
Sugar/
Glucose
Vitamin
s
Salt/
Sodium
Minerals
Body of the teenager:
Source:https://www.google.com.ph/search?biw=931&bih=414&tbm=isch&sa=1&q=whole+body+outline+of+a+teenage+boy&oq=whole+body+outli
ne+of+a+teenage+boy&gs_l=psy-ab.3...6369.14104.0.14978.18.18.0.0.0.0.215.2179.0j9j3.12.0....0...1.1.64.psyab..6.1.197...0i13k1.CoFpPDFnZb0#imgrc=yiFFfm28dXWWlM:
Guide Questions:
1. Describe the first illustration. The second.
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
2. What do you think will the first illustration feel if he ate the food for a longer period of time? How about
the second?
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
3. Which illustration do you think would best describe your nutrient intake? Is it healthy? If not, what will
you do to change the way you fill your body with nutrients?
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
WHAT I CAN DO ABOUT IT (APPLICATION)
Complete the sentence:
I need to eat nutritious food because
__________________________________________________________________________________
__________________________________________________________________________________.
WHAT I LEARNED (GENERALIZATION)
Write down in the box what you have learned from the lesson.
Reference:









https://lfsadem.files.wordpress.com/2012/03/liver-cell-005.jpg - picture of the muscle cell
http://images.slideplayer.com/33/8192541/slides/slide_8.jpg picture of muscle tissue
http://medimagery.com/anatomy/stomach/gastric_layers.png picture of stomach
https://humananatomy-libs.com/ picture of the digestive system
https://s-media-cache-ak0.pinimg.com/736x/41/72/9a/41729affcb93212b9f6020c8f434ea15--humandigestive-system-digestive-tract.jpg for figure 2
http://anatomywrap.com/wp-content/uploads/2016/12/human-digestive-system-without-labeled-digestivesystem-without-labels-thinglink-1.png
http://www.fnri.dost.gov.ph/index.php/tools-and-standard/nutritional-guide-pyramid#teen-13-19yrs-old
picture of FNRI Food pyramid
https://assets.rappler.com/612F469A6EA84F6BAE882D2B94A4B421/img/E2BF58689DCF45BA9BB1576
A59EBD3FF/school-foods-20170322.jpg - picture of street food
http://manilamed.com.ph/wp-content/uploads/2017/06/healthy-meals-for-kids.jpg - boy eating healthy food