SCI-IV Plant and Animal Systems

Science IV: Living Things : Animal and Plant Systems

Vocabulary Words

system – A group of parts that work together to do a specific job.

muscular system – The body system that helps you move by using

muscles.

skeletal system – The body system made up of bones that supports your

body and protects organs.

digestive system – The body system that breaks down food so your body

can use it for energy.

circulatory system – The body system that moves blood around your

body to deliver oxygen and nutrients.

respiratory system – The body system that helps you breathe in oxygen

and breathe out carbon dioxide.

root system – The part of a plant that grows below the ground and takes in

water and nutrients.

shoot system – The part of a plant that grows above the ground, including

stems, leaves, flowers, and fruits.

nutrients – Substances that living things need to grow and stay healthy.

oxygen – A gas from the air that humans and animals need to live.

Expanded Lesson: Systems in Plants and Animals

I. Human Body Systems

Your body is like a busy city — every part has a job to keep you alive and healthy. These jobs are done by systems, which are groups of organs working together. Let’s look at the five systems you need to know.

A. Muscular System

You have more than 600 muscles in your body, and they are always working — even when you are sleeping! Your muscles work together with your skeletal system so you can move, lift, jump, and even smile.

Example in real life: When you play patintero, your leg muscles help you run, and your arm muscles help you block your opponent.

Muscles are made of special tissue that can contract (shorten) and relax. This movement creates force, which allows your body to do all sorts of actions. Without muscles, you wouldn’t be able to walk to school, carry your school bag, or even write your name.

Three Types of Muscles in Your Body

Skeletal Muscles – Attached to your bones; they help you move. These are

muscles you can control.

Example: Your leg muscles when you play sipa or run in a school race.

Smooth Muscles – Found inside your organs (like your stomach and

intestines); they work automatically without you thinking about it.

Example: Your stomach muscles help digest pancit even while you’re sitting in class.

Cardiac Muscle – Found only in your heart; it works non-stop to pump blood

around your body.

Example: Your heart keeps beating when you’re sleeping, playing patintero, or doing homework.

How Do Muscles Work?

Muscles generate movement by contracting and relaxing. They pull on bones to produce motion, working in pairs to bend and straighten limbs. The nervous system initiates muscle contractions, and the structure of muscle fibers allows for this coordinated movement.

Muscles work in pairs — when one muscle contracts, the other relaxes. For example, when you bend your arm to eat lumpia, your biceps contract while your triceps relax.

Why is the Muscular System Important?

It helps you move and play.

It protects your joints and bones from injury.

It allows you to do everyday activities like climbing stairs or helping carry groceries.

It helps pump your blood (heart) and move food through your digestive system.

Healthy Habits for Strong Muscles

Eat foods rich in protein, like fish, chicken, eggs, munggo, and tofu.

Exercise regularly — run, swim, dance, or play sports.

Stretch before and after physical activities.

Drink enough water to keep your muscles hydrated.

Fun Facts (Did You Know?)

The strongest muscle (based on work done) is the heart — it beats around 100,000 times a day.

Your tongue is made up of several muscles working together.

The smallest muscle in your body is in your ear — it’s called the stapedius muscle.

Your eye muscles move about 100,000 times a day when you look around.

You use about 40 muscles just to smile — so keep smiling!

Try This!

Make a fist, then open your hand quickly. Feel your forearm — those are your muscles working.

Jump 10 times in place and feel your leg muscles tighten and relax.

B. Skeletal System

What is the Skeletal System?

Your skeletal system is made up of bones, joints, and cartilage. It is the framework of your body — just like the bamboo frame that supports a bahay kubo. Without your skeleton, you would be like a jellyfish, unable to stand, walk, or even sit.

Your skeletal system works closely with your muscular system so you can move. It also protects important organs inside your body.

Main Functions of the Skeletal System

Support – It gives your body shape and structure.

Example: Your spine keeps you upright when you sit at your school desk.

Movement – Bones work with muscles so you can run, jump, and dance.

Example: Your leg bones and muscles work together when you play luksong tinik.

Protection – Bones guard your internal organs.

Example: Your rib cage protects your heart and lungs like a shield.

Making Blood Cells – Inside some bones is bone marrow, which produces red blood cells (for carrying oxygen) and white blood cells (for fighting germs).

Storing Minerals – Bones store important minerals like calcium and phosphorus, which keep them strong.

Parts of the Skeletal System

Bones – Hard structures that give your body shape and support. An adult has 206 bones, but children have more because some bones fuse together as they grow.

Joints – Places where two bones meet, allowing movement (like knees and elbows).

Cartilage – Soft, rubbery tissue found in joints, nose, and ears that cushions bones and prevents them from rubbing together.

Healthy Habits for Strong Bones

Eat calcium-rich foods like milk, cheese, yogurt, and malunggay.

Get vitamin D from sunlight by playing outdoors in the morning.

Exercise regularly — walking, running, or playing outdoor games makes bones stronger.

Maintain good posture when sitting, walking, or studying.

Fun Facts : Did You Know?

Babies are born with about 300 bones, but as they grow, some join together until they have 206 bones as adults.

The largest bone in your body is the femur (thigh bone).

The smallest bone is the stapes in your middle ear — it’s smaller than a grain of rice.

Your bones are about five times stronger than steel of the same weight.

Every 7 to 10 years, your body replaces most of your old bone tissue with new bone tissue.

C. Digestive System

Your digestive system is the body’s food-processing machine. It breaks down the food you eat into smaller parts so your body can absorb the nutrients and use them for energy, growth, and repair.

Think of it like a kitchen in your body — where food is prepared, cooked, and turned into fuel so you can play, study, and grow strong.

How the Digestive System Works

The digestive system is like a long, twisty tube from your mouth to your anus. Here’s how food travels through it:

Mouth – Digestion starts here. Your teeth chew the food into smaller

pieces, and your saliva softens it.

Example: When you eat pandesal, your teeth crush it, and your saliva begins breaking it down.

Esophagus – A tube that connects your mouth to your stomach. Muscles

push food down in a wave-like motion called peristalsis.

Stomach – A bag-like organ that churns food and mixes it with digestive

juices to make it soft and mushy.

Example: Your stomach turns your lunch of rice and adobo into a mixture your body can process.

Small Intestine – A long, coiled tube where most nutrients are absorbed

into your blood.

Example: The vitamins from the vegetables in your pinakbet are absorbed here.

Large Intestine – Absorbs water from leftover food and turns it into solid

Anus – The final opening where waste leaves your body.

Why the Digestive System is Important

It turns food into energy so you can move, play, and think.

It gives your body nutrients to grow and stay healthy.

It removes waste so harmful substances don’t stay in your body.

Healthy Habits for a Strong Digestive System

Eat a balanced diet rich in vegetables, fruits, and whole grains.

Drink plenty of clean water.

Chew your food slowly and properly.

Avoid too much junk food or sugary drinks.

Be physically active to help digestion work better.

Fun Facts (Did You Know?)

Your small intestine is about 6 meters long — longer than the height of a classroom!

It takes about 24 to 72 hours for your body to fully digest a meal.

Your stomach produces strong acid that can dissolve some metals — but it’s safe because your stomach lining protects you.

If you spread out the small intestine flat, it would cover the size of a badminton court because of tiny folds and villi that absorb nutrients.

The growling sound in your stomach is called borborygmi, and it happens when your stomach muscles move and mix food or even just air.

D. Circulatory System

Your circulatory system is like the delivery service of your body. It moves blood, oxygen, and nutrients to every cell, and it carries away waste products. Without it, your body wouldn’t get the energy it needs to work.

This system is made up of your heart, blood vessels, and blood.

Main Parts of the Circulatory System

Heart – A strong muscle that pumps blood all over your body. It works

like a water pump, never stopping — even while you sleep.

Example: When you play luksong baka, your heart beats faster to send more oxygen to your muscles.

Blood Vessels – Tiny and large tubes that carry blood around the

body.

Arteries carry blood away from the heart.

Veins carry blood back to the heart.

Capillaries are the smallest blood vessels where oxygen and nutrients pass into your cells.

Blood – The red liquid that carries oxygen, nutrients, hormones, and

waste.

Red blood cells carry oxygen.

White blood cells fight germs.

Platelets help stop bleeding when you get a cut.

How the Circulatory System Works

When you breathe in, oxygen enters your lungs. The circulatory system picks up that oxygen from your lungs and delivers it to every cell in your body through the blood. At the same time, it carries away carbon dioxide and other waste to be removed from your body.

Why the Circulatory System is Important

It supplies oxygen and nutrients to all parts of your body.

It removes waste products that could harm your health.

It helps protect you from diseases by transporting white blood cells.

Healthy Habits for a Strong Circulatory System

Eat heart-healthy foods like fish, vegetables, fruits, and nuts.

Exercise regularly — skipping rope, dancing tinikling, or swimming keeps your heart strong.

Avoid too much oily and salty food.

Drink enough water to keep blood flowing well.

Get enough rest so your heart can recover from daily activities.

Fun Facts (Did You Know?)

Your heart is about the size of your fist but pumps around 7,000 liters of blood every day.

The average heart beats about 100,000 times a day — more than 35 million times a year!

If all your blood vessels were lined up, they could stretch over 96,000 kilometers — more than twice around the Earth.

Blood takes only about 20 seconds to travel around your whole body.

The sound of your heartbeat (“lub-dub”) is made by the heart valves opening and closing.

E. Respiratory System

Your respiratory system is your body’s breathing machine. It brings oxygen into your body when you inhale and removes carbon dioxide when you exhale. Every cell in your body needs oxygen to live, and your respiratory system works together with your circulatory system to deliver it.

Main Parts of the Respiratory System

Nose and Mouth – The main entrances for air. Tiny hairs in your nose filter dust and dirt.

Example: When you breathe in the smell of freshly cooked bibingka, air first passes through your nose.

Trachea (Windpipe) – The tube that carries air from your throat to your lungs.

Lungs – The main organs of breathing. You have two lungs — the right lung and the left lung. Inside are bronchi (air tubes) that branch into smaller bronchioles and end in tiny air sacs called alveoli, where oxygen enters the blood.

Diaphragm – A strong muscle under your lungs that moves up and down to help you breathe.

How the Respiratory System Works

You inhale (breathe in) oxygen-rich air through your nose or mouth.
Air travels down your trachea into your lungs.
Oxygen passes through the alveoli into your blood.
Your blood carries the oxygen to every cell in your body.
You exhale (breathe out) carbon dioxide, a waste gas.

Why the Respiratory System is Important

It supplies oxygen to your body for energy.

It removes carbon dioxide to keep you healthy.

It allows you to talk, sing, and laugh.

Healthy Habits for a Strong Respiratory System

Breathe through your nose to filter dust and germs.

Play outdoor games like patintero or habulan to strengthen your lungs.

Avoid smoking and stay away from cigarette smoke.

Eat foods rich in vitamins A and C (like carrots, oranges, and calamansi) for lung health.

Keep your surroundings clean to avoid dust and pollution.

Fun Facts (Did You Know?)

You breathe about 20,000 times a day without even thinking about it.

The surface area of your lungs is about the same size as a tennis court when spread out.

Your left lung is smaller than your right lung to make space for your heart.

Sneezes can travel up to 160 kilometers per hour — faster than many cars on EDSA!

Singing can improve your lung capacity, which is why choir singers often have strong lungs.

Assessment: Muscular System

Part A – Vocabulary (5 points)

Match the term to its correct meaning. Write the letter of your answer.

A. Skeletal Muscles

B. Smooth Muscles

C. Cardiac Muscle

D. Contract

E. Relax

_____1. The muscle type found only in the heart.

_____2. The muscle type you can control that moves your bones.

_____3. When a muscle shortens to create movement.

_____4. The muscle type found in the stomach and intestines.

_____5. When a muscle lengthens after movement.

Part B – Identification (5 points)

Write the correct answer in the blank.

How many muscles are in the human body?

6. _________________________________

Which system works closely with the muscular system to allow movement?

7. _________________________________

Name one activity where you use your leg muscles.

8. _________________________________

What nutrient is important for muscle growth?

9. _________________________________

What is the main job of muscles?

10. _________________________________

Part C – Answer each question in 2–3 sentences.

Explain why muscles work in pairs. Give an example from your daily activities.

Why is it important to exercise regularly for your muscles?

Part D – Critical Thinking (5 points)

Read the situation and answer the question.

Situation: You are playing luksong tinik during recess. Your leg muscles start to feel tired after several jumps.

What is happening to your muscles, and what should you do to keep them strong and healthy?

Assessment: Skeletal System

Part A – Vocabulary (5 points)

Match the term to its correct meaning. Write the letter of your answer.

A. Bones

B. Joints

C. Cartilage

D. Bone Marrow

E. Calcium

_____1. Soft, rubbery tissue that cushions bones; found in the nose and ears.

_____2. Hard structures that give your body shape and protect organs.

_____3. Mineral stored in bones that keeps them strong.

_____4. Places where two bones meet, allowing movement.

_____5. Soft tissue inside bones that makes blood cells.

Part B – Identification (5 points)

Write the correct answer in the blank.

How many bones does an adult human have?

6. ________________________

Name one function of the skeletal system that protects the organs.

7. ________________________

Which bone is the largest in the human body?

8. ________________________

Which bone is the smallest in the human body?

9. ________________________

What vitamin helps the body absorb calcium for strong bones?

10. _______________________

Part C – Short Answer (5 points)

Answer each question in 2–3 sentences.

Explain why bones need calcium and vitamin D. Give examples of local foods that provide them.

How does the skeletal system work together with the muscular system to allow movement?

Part D – Critical Thinking (5 points)

Read the situation and answer the question.

Situation: You see a classmate slouching while doing schoolwork.

What advice would you give them to protect their skeletal system, and why is posture important?

Assessment: Digestive System

Part A – Vocabulary (5 points)

Match the term to its correct meaning. Write the letter of your answer.

A. Mouth

B. Stomach

C. Small Intestine

D. Large Intestine

E. Esophagus

_____1. The first part of the digestive system where food is chewed and

mixed with saliva.

_____2. Long tube where most nutrients from food are absorbed into the

blood.

_____3. Tube that carries food from the mouth to the stomach.

_____4. Organ that churns food and mixes it with digestive juices.

_____5. Part of the digestive system that absorbs water and forms solid

waste.

Part B – Identification (5 points)

Write the correct answer in the blank.

What is the main job of the digestive system?

6. _____________________

What is the process of moving food down the esophagus called?

7. _____________________

Name one local food that provides fiber for healthy digestion.

8. _____________________

Which organ produces strong acid to help break down food?

9. _____________________

What is the last part of the digestive system where waste leaves the body?

10. ____________________

Part C – Short Answer (5 points)

Answer each question in 2–3 sentences.

Why is chewing food properly important for digestion?

How does drinking enough water help the digestive system?

Part D – Critical Thinking (5 points)

Read the situation and answer the question.

Situation: After eating a big meal during a fiesta, you feel too full and sleepy.

What is happening inside your digestive system, and what can you do to help it work better after large meals?

Assessment: Circulatory System

Part A – Vocabulary (5 points)

Match the term to its correct meaning. Write the letter of your answer.

A. Heart

B. Arteries

C. Veins

D. Capillaries

E. Red Blood Cells

_____1. Blood vessels that carry blood away from the heart.

_____2. The smallest blood vessels where oxygen and nutrients move into the

cells.

_____3. The muscle that pumps blood all over the body.

_____4. Blood vessels that carry blood back to the heart.

_____5. Cells in the blood that carry oxygen.

Part B – Identification (5 points)

Write the correct answer in the blank.

What is the main job of the circulatory system?

6. _____________

Which part of the blood helps fight germs?

7. ________________

Name one local food that is good for heart health.

8. _________________

What gas do red blood cells carry to the body’s cells?

9. ___________________

Which two systems work closely to deliver oxygen throughout the body?

10. ______________

Part C – Short Answer (5 points)

Answer each question in 2–3 sentences.

Why does your heart beat faster when you exercise?

How do white blood cells protect your body from illness?

Part E – Critical Thinking (5 points)

Read the situation and answer the question.

Situation: You are running a race during Sports Day. Halfway through, you start breathing heavily and your heart beats fast.

Explain how your circulatory system is helping you during this activity and why it’s important for you to cool down after.

Assessment: Respiratory System

Part A – Vocabulary (5 points)

Match the term to its correct meaning. Write the letter of your answer.

A. Lungs

B. Diaphragm

C. Trachea

D. Alveoli

E. Oxygen

_____1. The main organs of breathing that take in oxygen and release carbon

dioxide.

_____2. The gas you inhale that your body needs to survive.

_____3. Tiny air sacs in the lungs where oxygen enters the blood.

_____4. The strong muscle under your lungs that helps you breathe.

_____5. The windpipe that carries air from your throat to your lungs.

Part B – Identification (5 points)

Write the correct answer in the blank.

What is the main job of the respiratory system?

6. ______________

Which gas do you release when you exhale?

7. __________________

Name one activity that can help strengthen your lungs.

8. _______________

Which system works closely with the respiratory system to deliver oxygen to your body?

9.__________________

Which part of the respiratory system filters dust when you breathe in?

10. _____________

Part C – Short Answer (5 points)

Answer each question in 2–3 sentences.

How does the respiratory system work together with the circulatory system to keep you alive?

Why is it important to keep your surroundings clean for your respiratory health?

Part D – Critical Thinking (5 points)

Read the situation and answer the question.

Situation: You are singing in your school’s Buwan ng Wika program. You take deep breaths between lines.

Explain how your respiratory system is helping you sing and why breathing techniques are important for performances.

Root System and Shoot System in Plants

What are Plant Systems?

Just like animals and humans have body systems to survive, plants also have systems that help them live, grow, and reproduce. These systems work together to get food, water, and sunlight, and to protect the plant from harm.

Plants have two main systems:

Root System – The part of the plant that grows below the ground.

Shoot System – The part of the plant that grows above the ground.

1. Root System

The root system is the underground part of the plant. It has three main jobs:

Functions of the Root System

Anchoring – Roots hold the plant firmly in the soil so it doesn’t get blown away

by wind or washed away by rain.

Example: In the rice paddies of Iloilo, rice roots keep the plants steady even during strong rains.

Absorbing Water and Nutrients – Roots take in water and minerals from

the soil, which are sent to the rest of the plant.

Example: The roots of a calamansi tree absorb water after you water it in the garden.

Storing Food – Some roots store food for the plant.

Example: Sweet potato (kamote) roots store starch, which we can eat.

Types of Roots

Taproot – One main thick root growing straight down with smaller side roots.

Example: Carrot (karot) and radish (labanos).

Fibrous Roots – Many thin roots that spread out in all directions.

Example: Rice (palay) and onion (sibuyas).

2. Shoot System

The shoot system is the part of the plant above the ground. It includes the stem, leaves, flowers, and fruits.

Functions of the Shoot System

Supporting the Plant – Stems hold up the leaves, flowers, and fruits so they can get sunlight.

Example: The stem of a sunflower holds up its large flower to face the sun.

Transporting Water and Nutrients – Stems act like highways, carrying water from the roots to the leaves and food from the leaves to the rest of the plant.

Photosynthesis – Leaves make food for the plant using sunlight, water, and carbon dioxide.

Example: The leaves of a malunggay tree use sunlight to make nutrients for growth.

Reproduction – Flowers produce seeds for new plants. Fruits protect seeds and help them spread.

Example: A mango tree’s flowers turn into fruits that we eat, and inside are seeds that can grow into new mango trees.

Why Are Root and Shoot Systems Important?

If roots are damaged, the plant cannot absorb enough water and will wilt. If stems or leaves are damaged, the plant cannot make food through photosynthesis. Both systems must be healthy for the plant to survive.

Healthy Habits for Plants