science chap 9. Respiration in organisms workbook question -ans

9. Respiration in organisms

1.	Choose the correct option:
a)	Which of the following prevents food particles from entering into the trachea? (An)
(a)	Pharynx	(b)	Cilia
(c)	Larynx	(d)	Epiglottis
ans:	Epiglottis
b)	The CORRECT word equation for aerobic respiration in plants is: (An)
(a)	carbon dioxide + water →glucose + oxygen
(b)	glucose + carbon dioxide →water + oxygen
(c)	glucose + oxygen →carbon dioxide + water
(d)	glucose + water →carbon dioxide + oxygen
ans:	glucose + oxygen → carbon dioxide + water
c)	The ___________ separates the chest cavity from the abdomen. (R)
(a)	oesophagus	(b)	diaphragm
(c)	larynx	(d)	trachea
ans:	diaphragm
d)	Which of the following organisms respire through the tracheal system? (An)
(a)	Earthworm	(b)	Cockroach
(c)	Leech	(d)	Dog
ans:	Cockroach
2.	State whether the following statements are true or false. Correct the false statements.(U)
a)	Living things require energy for different life processes.
ans:	True

b)	Mature frogs can breathe through their skin as well as through their lungs.
ans:	True
c)	In fish, a hard and bony operculum protects the lungs.
ans:	False, In fish, a hard and bony operculum protects the gills.
d)	Lungs are air-filled sac-like structures in the chest cavity.
ans:	True

3.	In the following questions, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Read the statements carefully and choose the correct alternative (A), (B), (C) and (D) as given below. (An/E)
(A) Both A and R are true and R is the correct explanation of the assertion. (B) Both A and R are true but R is not the correct explanation of the assertion. (C) A is true but R is false. (D) A is false but R is true.
a)	Assertion: Lime water turns milky when we blow air into it.
Reason: The air we breathe out is rich in carbon dioxide.
ans:	(A) Both A and R are true and R is the correct explanation of the assertion.
b)	Assertion: A massage can help during cramps.
Reason: Massage helps in improving blood circulation and increases the supply of oxygen.
ans:	(B) Both A and R are true and R is the correct explanation of the assertion.
c)	Assertion: Haemoglobin combines with oxygen to form oxyhaemoglobin.
Reason: White blood cells contain haemoglobin.
ans:	Assertion is true but the Reason is false.

4.	State one function for each of the following: (U)
a)	Cilia in the nasal cavity

ans:	The cilia help in filtering and trapping any pollutants, dust particles and germs that enter along with the inhaled air.
b)	Alveoli
ans:	• Alveoli make the lungs spongy and elastic. • Help in exchange of oxygen and carbon dioxide in the lungs.
(answer may vary, accept all correct answers)
c)	Capillaries that lie close to the skin surface of earthworms.
ans:	These capillaries transport oxygen to various tissues and carry carbon dioxide to the outer skin layer.
5.	Answer the following questions: (R, E, U)
(a)	Name the following: i) tiny pores on the leaves of plants through which gas exchange occurs ii) tiny pores on stems of plants through which gas exchange occurs
ans:	i) stomata ii) Lenticels
(b)	Define the term cellular respiration.
ans:	The breakdown of food (glucose) in the presence of oxygen to release energy is called cellular respiration.
(c)	Why do farmers turn the soil at regular intervals?
ans:	Farmers turn the soil at regular intervals to make the soil loose. This allows the roots to take in the oxygen present in the soil by diffusion.
(d)	Briefly describe the structure and function of the gills.
ans:	• Structure: → Gills are made of filaments which look like the teeth of a comb. → They are richly supplied with blood capillaries and are highly folded to increase the surface area for gaseous exchange. • Function: Gills help fish use the oxygen dissolved in water.

6.	Label the different parts of the human respiratory system.(Rrfer to textbook)
7.	Paul, the baker was making bread. He added yeast to the dough and left it in a warm place. After few hours, he observed that the dough had risen. (Ap)
a)	What type of respiration takes place in the dough due to the addition of yeast?
ans:	anaerobic respiration
b)	Why did the dough rise?
ans:	The dough rises due to the release of carbon dioxide during anaerobic respiration by the yeast cell.

8.	WORD SEARCH: Find the hidden words related to respiration in organisms by using the clues given below. The words may be present in any direction – upwards, downwards or diagonally. (Ap)
K L F G Y U R I A R K F A D G T Y L I R A F S L T E J R A E B Y E U A U P R Y R U D S R G N T N T F Y E D G I A W O R G D N T I E C H K A S A S X E R G Y P A C G T C K T T Y B O D T W A R H F G I H S M G U E H I E I H L E R O H L T U L A X S O R T W B M R U S I D H A E M O G L O B I N K
Clues: 1. The air tubes of insects 2. Skeletal structures that surround the chest cavity and protect the lungs 3. The respiratory organs of human beings 4. The openings through which we inhale 5. The energy currency of cells 6. The food pipe 7. Voice box 8. The pigment present in red blood cells
9.	Aerobic respiration is more efficient than anaerobic respiration. Justify. (An/E)
ans:	During aerobic respiration, a single molecule of glucose yields 38 ATP molecules whereas, in anaerobic respiration or fermentation, only 2 molecules of ATP are produced from one molecule of glucose, which in comparison is lesser than aerobic respiration. Hence aerobic respiration is more efficient.

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