Short Answer Questions Human Body Organ Systems - Science for Class 3

Q1: What are the tiny building blocks of the human body called?
Ans: The tiny building blocks of the human body are called cells. Cells are very small and we cannot see them with our eyes. Many similar cells join together to make tissues.

Q2: What does the skeletal system give to our body?
Ans: The skeletal system gives our body shape and support. It also protects some inner organs and works with muscles to help us move. Adults have 206 bones.

Q3: How do bones protect our body?
Ans: Bones protect important organs like the brain, heart, and lungs. For example, the skull protects the brain, the ribcage protects the heart and lungs, and the backbone protects the spinal cord.

Q4: What is the job of the muscular system?
Ans: The muscular system helps us move our body parts. It has over 600 muscles. Muscles are soft parts that connect to bones and help us move, like blinking, walking, or jumping. Some muscles work without us thinking, for example the heart keeps beating all the time.

Q5: What does the digestive system do with food?
Ans: The digestive system breaks down food into simpler forms that the body can use for energy to do daily activities. The main parts are the mouth, stomach and intestines. The body takes nutrients from the food to grow and stay active.

Q6: What are the main parts of the circulatory system?
Ans: The circulatory system includes the heart, blood, and blood vessels. It carries oxygen and nutrients to all parts of the body and takes away waste like carbon dioxide.

Q7: How does the respiratory system help us?
Ans: The respiratory system helps us breathe. It uses the nose, windpipe, and lungs to take in oxygen and to remove carbon dioxide when we breathe out.

Q8: What does the nervous system control?
Ans: The nervous system controls all organs with the brain, spinal cord, and nerves. It sends messages around the body so we can think, feel, move and learn.

Q9: Name two sense organs and their functions.
Ans: Two sense organs are:

1. Eyes: Our eyes help us see things. They show us pictures of the world around us, such as shapes, sizes and colours.

2. Ears: Our ears allow us to hear sounds. They help us listen to voices, music and other noises.

Q10: What does the excretory system remove from the body?
Ans: The excretory system removes waste like urine, sweat, and carbon dioxide. The kidneys make urine, the skin makes sweat, and the lungs remove carbon dioxide to keep the body clean.