Class 9 Science Chapter 5: The Fundamental Unit of Life (NERT)
This chapter explore cells, their structure, and functions. It introduces the concept of cell as basic unit of life and discusses the cell theory proposed by Schleiden, Schwann, and Virchow. The Chapter covers the different types of cells, their shapes, and sizes along with a detailed study of cell organelles such as:
- Plasma Membrane: Semi-permeable membrane that controls the movement of substances.
- Cell Wall: Found in plant cells, providing rigidity and protection.
- Cytoplasm: The jelly-like substance where organelles are suspended.
- Nucleus: The control centre of the cell, containing DNA and regulating cell activities.
- Mitochondria: The powerhouse of the cell, generating ATP.
- Endoplasmic Reticulum (ER): Rough ER (with ribosomes) aids in protein synthesis, while Smooth ER helps in lipid synthesis.
- Golgi Apparatus: Packages and transport proteins.
- Plastids: Present only in plant cells; chloroplasts help in photosynthesis.
- Vacuoles: Storage sacs; large in plant cells, small in animal cells.
Most Important MCQs Type Questions and Answers
Ques 1: Which of the following is NOT a characteristic ofliving organisms?
(a) Growth
(b) Reproduction
(c) Respiration
(d) Decay
Ques 2: What is the basic unit of life in an organism?
(a) Organ
(b) Cell
(c) Tissue
(d) Organ system
Ques 3: Which process is responsible for the breakdown of food to release energy?
(a) Nutrition
(b) Digestion
(c) Respiration
(d) Excretion
Ques 4: Which of the following is an autotroph?
(a) Humans
(b) Fungi
(c) Green plants
(d) Amoeba
Ques 5: Photosynthesis mainly takes place in which part of the plant?
(a) Roots
(b) Stem
(c) Leaves
(d) Flowers
Ques 6: What is the main pigment involved in photosynthesis?
(a) Haemoglobin
(b) Chlorophyll
(c) Carotene
(d) Xanthophyll
Ques 7: The raw material for photosynthesis are:
(a) Carbon dioxide and oxygen
(b) Carbon dioxide and water
(c) Oxygen and water
(d) Oxygen and nitrogen
Ques 8: Which organ in humans produces bile?
(a) Pancreas
(b) Liver
(c) Stomach
(d) Small intestine
Ques 9: Which enzyme is saliva helps in the digestion of starch?
(a) Pepsin
(b) Amylase
(c) Trypsin
(d) Lipase
Ques 10: The process of movement of food through the alimentary canal is called:
(a) Diffusion
(b) Absorption
(c) Peristalsis
(d) Excretion
Ques 12: What is the function of the villi present in the small intestine?
(a) Absorb water
(b) Absorb nutrients
(c) Absorb bile
(d) Digest
Ques 13: The waste product of aerobic respiration in humans is:
(a) Carbon dioxide and water
(b) Oxygen and water
(c) Lactic acid
(d) Alcohol and carbon dioxide
Ques 14: Which part of the human respiratory system is responsible for gas exchange?
(a) Trachea
(b) Bronchi
(c) Alveoli
(d) Diaphragm
Ques 15: Which of the following organisms perform anaerobic respiration?
(a) Plants
(b) Animals
(c) Yeast
(d) Birds
Ques 16: The functional unit of the kidney is called:
(a) Nephron
(b) Alveoli
Ureter
Glomerulus
Ques 17: Which of the following in NOT an excretory organ in humans?
(a) Liver
(b) Lungs
(c) Kidney
(d) Stomach
Ques 18: In which of the following organisms does the exchange of gases take place through moist skin?
(a) Frog
(b) Fish
(c) Humans
(d) Insects
Ques 19: The opening and closing of stomata is controlled by:
(a) Xylem
(b) Pholem
(c) Guard cells
(d) Root hairs
Ques 20: Which of the following is a product of anaerobic respiration in muscles?
(a) Ethanol
(b) Lactic acid
(c) Carbon dioxide
(d) Water
Answers with Explanation
Answer 1: (d) Decay
Explanation: Living organisms show growth, reproduction, and respiration. Decay is a process that occurs after death due to microbial activity.
Answer 2: Cell
Explanation: The cell is the smallest structural and functional unit of life. All living beings are made up of cells.
Answer 3: (c) Respiration
Explanation: Respiration is the process of breaking down glucose to release energy in the form of ATP (Adenosine Triphosphate).
Answer 4: (c) Green plants
Explanation: Autotrophs, like green plants, can prepare their own food through photosynthesis, unlike fungi, amoeba, or humans.
Answer 5: (c) Leaves
Explanation: Leaves contain chlorophyll, which traps sunlight and helps in photosynthesis.
Answer 6: (b) Chlorophyll
Explanation: Chlorophyll absorbs light energy for photosynthesis, giving plants their green color.
Answer 7: (b) Carbon dioxide and water
Explanation: Plants use carbon dioxide from the air and water from the soil to produce glucose and oxygen in the presence of sunlight.
Answer 8: (b) Liver
Explanation: The liver produces bile, which helps in the digestion of fats by breaking them into smaller droplets.
Answer 9: (b) Amylase
Explanation: Salivary amylase (also called ptyalin) breaks down starch into simple sugars in the mouth.
Answer 10: (c) Peristalsis
Explanation: Peristalsis is the rhythmic contraction and relaxation of muscles in the digestive tract, pushing food forward.
Answer 11: (c) Small intestin
Explanation: The small intestine completes the digestion of carbohydrates, proteins and fats with the help of digestive enzymes.
Answer 12:(b) Absorb nutrients
Explanation: Villi increase the surface area for nutrient absorption into the blood.
Answer 13: (a) Carbon dioxide and water
Explanation: In aerobic respiration, glucose is completely broken down into carbon dioxide and water, releasing energy.
Answer 14: (c) Alveoli
Explanation: Alveoli are tiny air sacs in the lungs where oxygen enters the blood and carbon dioxide is removed.
Answer 15: (c) Yeast
Explanation: Yeast performs anaerobic respiration, producing ethanol and carbon dioxide in the absence of oxygen.
Answer 16: (a) Nephron
Explanation: Nephrons filter waste from the blood and form urine in the kidneys.
Answer 17: (d) Stomach
Explanation: The kidney, lungs, and liver remove waste, but the stomach is part of digestion, not excretion.
Answer 18: (a) Frog
Explanation: Frogs use their skin for respiration when in water, as it remains moist and helps in gas exchange.
Answer 19: (c) Guard cells
Explanation: Guard cells regulate the opening and closing of stomata to control gas exchange and water loss.
Answer 20: (b) Lactic acid
Explanation: During anaerobic respiration in muscles (due to lack of oxygen), glucose is broken down into lactic acid, causing muscle fatigue.