Class V worksheet on organ systems that help us move, featuring questions on anatomy and physiology.

Let's solve each question from the EVS (Environmental Studies) worksheet for Class V, step by step, with explanations.

---

Q. 1 Fill in the blanks:

a. The air we breathe in passes from the wind pipe to the _____.
✔ Answer: *Lungs*
🔹 Explanation: After entering through the nose or mouth, air travels down the trachea (windpipe) and reaches the lungs, where gas exchange occurs.

b. The thigh bone is connected to the hip by a _____.
✔ Answer: *Ball and socket joint*
🔹 Explanation: The femur (thigh bone) connects to the pelvic bone at the hip via a ball-and-socket joint, allowing wide range of motion.

c. _____ pairs of ribs make up a rib cage.
✔ Answer: *12*
🔹 Explanation: Humans have 12 pairs (24 individual) ribs that protect the heart and lungs.

d. Urine leaves the kidneys through the _____.
✔ Answer: *Ureters*
🔹 Explanation: Urine formed in the kidneys flows through two tubes called ureters into the urinary bladder.

e. There are _____ bones in an adult’s body.
✔ Answer: *206*
🔹 Explanation: An adult human has 206 bones. This number reduces from childhood (around 270) due to fusion of certain bones.

---

Q. 2 Name the following:

a. Instrument used by the doctors to hear the heart beat.
✔ Answer: *Stethoscope*
🔹 Used to listen to internal sounds like heartbeat and breathing.

b. Number of bones in the skull.
✔ Answer: *22*
🔹 Includes 8 cranial bones and 14 facial bones.

c. Sticky substance inside the nose which helps to filter the dust.
✔ Answer: *Mucus*
🔹 Mucus traps dust, bacteria, and other particles inhaled through the nose.

d. The organ of the digestive system where most of the digestion takes place.
✔ Answer: *Small intestine*
🔹 Most chemical digestion and nutrient absorption happen here.

e. The opening through which faeces pass out of the body.
✔ Answer: *Anus*
🔹 The end of the digestive tract; waste exits through the anus.

---

Q. 3 Define the following:

a. Organ system
✔ Answer: A group of organs working together to perform a specific function.
🔹 Example: Digestive system includes mouth, stomach, intestines, etc.

b. Digestion
✔ Answer: The process of breaking down food into smaller substances so they can be absorbed by the body.
🔹 Involves mechanical and chemical processes.

c. Excretion
✔ Answer: The removal of waste products from the body.
🔹 E.g., urine (kidneys), sweat (skin), feces (rectum).

d. Joint
✔ Answer: A place where two or more bones meet.
🔹 Allows movement and supports structure.

e. Vertebrae
✔ Answer: The bones that make up the spine or backbone.
🔹 Protects the spinal cord and supports the body.

f. Respiration
✔ Answer: The process by which living organisms take in oxygen and release carbon dioxide.
🔹 Includes breathing and cellular respiration.

---

Q. 4 Write the functions of:

a. Spinal cord
✔ Answer: It carries messages between the brain and the rest of the body. Also controls reflex actions.
🔹 Acts as a pathway for nerve signals.

b. Kidneys
✔ Answer: Filter blood to remove waste and excess water, forming urine. Regulate blood pressure and balance electrolytes.
🔹 Maintain homeostasis.

c. Skeletal system
✔ Answer: Supports the body, protects internal organs, allows movement, produces blood cells, and stores minerals.
🔹 Bones provide structure and strength.

---

Q. 5 Differentiate between:

a. Internal & external organs
| Internal Organs | External Organs |
|---------------------|----------------------|
| Located inside the body | Located outside the body |
| E.g., Heart, lungs, liver | E.g., Skin, eyes, ears |
| Protected by bones or tissues | Directly exposed |

b. Veins and arteries
| Veins | Arteries |
|---------|------------|
| Carry blood toward the heart | Carry blood away from the heart |
| Have valves to prevent backflow | No valves (except in some cases) |
| Carry deoxygenated blood (except pulmonary veins) | Carry oxygenated blood (except pulmonary arteries) |

c. Voluntary and involuntary muscles
| Voluntary Muscles | Involuntary Muscles |
|------------------------|--------------------------|
| Controlled consciously | Work automatically |
| Found in limbs (skeletal) | Found in internal organs (smooth, cardiac) |
| E.g., Biceps | E.g., Heart muscle, stomach lining |

d. Ball and socket joint & hinge joint
| Ball and Socket Joint | Hinge Joint |
|----------------------------|------------------|
| Allows movement in all directions | Allows movement in one direction (like a door) |
| E.g., Shoulder, hip | E.g., Elbow, knee |

---

Q. 6 Name the four different types of teeth that we have along with their numbers and functions.

| Type of Tooth | Number | Function |
|--------------------|-----------|--------------|
| Incisors | 8 (4 upper, 4 lower) | Cut food |
| Canines | 4 (2 upper, 2 lower) | Tear food |
| Premolars | 8 (4 upper, 4 lower) | Crush and grind food |
| Molars | 12 (6 upper, 6 lower) | Grind food thoroughly |

🔹 Note: Total = 32 permanent teeth (in adults). Children have 20 milk teeth.

---

Q. 7 Explain in a few lines:

a. What happens to food in the mouth?
✔ Food is chewed by teeth and mixed with saliva. Saliva contains enzymes (like amylase) that begin breaking down starch into simpler sugars. Tongue helps in mixing and swallowing.

b. How does exercise help your muscles?
✔ Exercise strengthens muscles, improves endurance, increases flexibility, and helps maintain healthy muscle mass. Regular activity makes muscles work efficiently and grow stronger over time.

c. How do living beings get energy from food?
✔ During digestion, food is broken down into simple substances like glucose. These are absorbed into the bloodstream and used in cells during respiration to produce energy (ATP). Oxygen is required for this process.

---

Q. 8 Draw and label the diagrams of Digestive and Urinary system.

Since I cannot draw images here, I’ll describe how to draw them clearly:

#### ✔ Digestive System Diagram (to draw):
1. Start from the mouth → pharynx → esophagus → stomach → small intestine → large intestine → rectum → anus.
2. Include liver, gallbladder, pancreas (they secrete juices).
3. Label each part clearly.

#### ✔ Urinary System Diagram (to draw):
1. Show two kidneys on either side of the spine.
2. From each kidney → ureter → urinary bladder → urethra → outside the body.
3. Label: Kidneys, ureters, bladder, urethra.

🔹 You can sketch these using simple shapes and arrows showing flow.

---

✔ Summary of Answers:

This worksheet tests understanding of organ systems, especially digestive and excretory systems, and musculoskeletal system. It covers:
- Basic anatomy
- Functions of organs
- Types of joints and teeth
- Differences between body structures
- Processes like digestion and respiration

---

Let me know if you'd like printable versions or diagrams drawn digitally!