Keywords To Remember
Respiration-related Keywords & Definitions
- Respiration
The process by which organisms convert glucose into energy, using oxygen, and release carbon dioxide and water as by-products. - Cellular Respiration
The breakdown of glucose within cells to release energy. This usually involves oxygen and occurs in all living organisms. - Aerobic Respiration
The process of producing energy from food (glucose) in the presence of oxygen. - Anaerobic Respiration
The process of producing energy from food (glucose) in the absence of oxygen. - Fermentation
A type of anaerobic respiration, commonly occurring in yeast, that produces alcohol and carbon dioxide. - Oxygen Debt
The extra oxygen the body needs after strenuous activity to break down lactic acid and restore the body to normal. - Lactic Acid
A substance produced in muscles during anaerobic respiration in humans; it causes muscle cramps and fatigue.
Breathing & Lungs-related Keywords
- Breathing (External Respiration)
The process of inhaling air rich in oxygen and exhaling air rich in carbon dioxide. - Inhalation (Inspiration)
The act of taking air into the lungs, which is rich in oxygen. - Exhalation (Expiration)
The act of pushing air out from the lungs, which is rich in carbon dioxide. - Breathing Rate
The number of breaths (one inhalation + one exhalation) taken per minute. - Lungs
Spongy organs located in the chest that facilitate gas exchange during breathing. - Diaphragm
A dome-shaped muscle below the lungs that plays a key role in breathing by moving up and down. - Rib Cage
The structure surrounding the lungs and heart, helping in breathing by expanding and contracting. - Haemoglobin
A red pigment in red blood cells that binds with oxygen and transports it to body parts; also helps carry carbon dioxide back to the lungs.
Plant-related Keywords
- Stomata
Small pores on the surface of leaves that allow the exchange of gases (oxygen and carbon dioxide) and water vapor. - Lenticels
Small pores present on the woody stems of plants that allow gas exchange. - Transpiration
The process by which plants lose excess water through open stomata, helping regulate water and temperature.
Gas Exchange & Organisms
- Diffusion
A passive process through which gases like oxygen and carbon dioxide move across cell membranes. - Gills
Respiratory organs found in fish and aquatic animals that extract oxygen from water. - Tracheae
A network of air tubes in insects used for the exchange of gases. - Opercula
Flap-like structures in fish that cover and protect the gills and help in controlling water flow. - Lamellae
Thin, plate-like structures in fish gills where the actual gas exchange takes place.
Other Important Terms
- Energy
The ability to do work; in biology, energy is released by the breakdown of glucose during respiration. - Glucose
A simple sugar that is a primary source of energy for cells during respiration. - Carbon Dioxide (CO₂)
A gas released as a waste product during respiration. - Oxygen (O₂)
A gas essential for aerobic respiration, taken in during inhalation. - Alcohol
A by-product of anaerobic respiration in yeast; used in beverages and baking. - Cramps
Sudden, involuntary muscle contractions often caused by lactic acid buildup. - Yawn
A deep breath taken involuntarily, often due to lack of oxygen in the lungs, which increases oxygen intake. - Cough/Sneeze
Reflex actions to expel irritants from the respiratory tract, like dust or microbes. - Nicotine
A harmful chemical found in tobacco that affects respiratory and cardiovascular systems. - Carbon Monoxide (CO)
A poisonous gas produced by burning tobacco; it binds with haemoglobin and reduces oxygen transport. - Tar
A sticky substance in tobacco smoke that damages lung tissues and airways.
Something To Know
A. Fill in the blanks.
- Lactic acid is produced during __________ respiration.
Answer – anaerobic
- Insects have organs, called__________ for respiration.
Answer – tracheae
- Taking in of air, rich in oxygen, is called __________ .
Answer – inhalation
- An adult human being normally breathes from __________ to __________ times per
minute.
Answer – 12 to 20
- The movement of lungs is controlled by the __________ and the __________ .
Answer – diaphragm, intercostal muscles.
- __________ acts as the respiratory carrier in our body.
Answer – Haemoglobin
B. Match the following:
- Lactic acid (a) Transpiration
- Stomata (b) Pores on branches
- Respiratory carrier (c) Muscle cramps
- Lenticles (d) Fermentation of yeast
- Alcohol (e) Haemoglobin
Answer –
Lactic acid – (c) Muscle cramps
Stomata – (a) Transpiration
Respiratory carrier – (e) Haemoglobin
Lenticles – (b) Pores on branches
Alcohol – (d) Fermentation of yeast
C. Tick (✓) the correct option.
- Respiration helps in—
locomotion
absorption
digestion
obtaining energy
Answer – obtaining energy
- Stomata perform the function of—
absorption of water
exchange of gases
absorption of minerals
movement of food
Answer – exchange of gases
- The process represented by the following equation,
(glucose + oxygen * carbon dioxide + water + energy)
is photosynthesis
is fermentation
is transpiration
is aerobic respiration
Answer – aerobic respiration
- To survive, plant roots need–
carbon dioxide
Chlorophyll
oxygen
sunlight
Answer – oxygen
- Earthworms and leeches respire through their—
lungs
trachea
gills
skin
Answer – skin
D. Answer the following questions in brief.
- Define respiration. Name the two types of respiration.
Answer – Respiration is the process by which living organisms release energy from food.
The two types of respiration are:
(a) Aerobic respiration
(b) Anaerobic respiration
- Name the respiratory organ of the following:
(a) crab
Answer – Gills
(b) man
Answer – Lungs
(c) leech
Answer – Skin
(d) an insect
Answer – Tracheae
- Define transpiration.
Answer – Transpiration is the process by which plants lose water in the form of water vapour through small pores called stomata.
- Define the term ‘breathing rate’.
Answer – Breathing rate is the number of times a person breathes (inhales and exhales) in one minute.
- Name the body organs which help lungs during the process of breathing.
Answer – The diaphragm and intercostal muscles help the lungs during breathing.
- Why do we need to breathe out carbon dioxide?
Answer – We need to breathe out carbon dioxide because it is a waste gas produced during respiration and can be harmful if it builds up in the body.
E. Answer the following questions
- Why do we get muscle cramps after heavy excercise?
Answer – During heavy exercise, the body may not get enough oxygen, so anaerobic respiration occurs in muscles producing lactic acid, which causes cramps.
- Why does a potted plant die when over watered?
Answer – Overwatering fills the air spaces in soil, cutting off oxygen supply to roots, which are unable to respire and die.
- Where are stomata found in a plant? State their function.
Answer – Stomata are found mainly on the underside of leaves. They help in exchange of gases and transpiration.
- How is oxygen transported from lungs to the other parts of the body?
Answer – Oxygen is transported by haemoglobin in red blood cells from the lungs to other body parts through the bloodstream.
- Draw a neat, well-labelled diagram of the human respiratory system.
Answer – (You can draw this yourself or ask me for a labeled diagram and I’ll generate it.)
- Describe an activity to show that exhaled air contains carbon dioxide.
Answer – Activity: Blow air into lime water using a straw. Lime water turns milky, showing the presence of carbon dioxide in exhaled air.
- Describe the changes that take place (i) around the rib cage (ii) diaphragm (iii) chest cavity, during inspiration. State the effect of these changes.
Answer – (i) Rib cage: Moves upward and outward
(ii) Diaphragm: Contracts and moves downward
(iii) Chest cavity: Increases in volume
Effect: Air rushes into the lungs as pressure inside decreases.
Value Based Question
It was time for the 400 m race in the annual athletic meet of the school. Shweta, who was tipped to win the race, maintained a clear lead over others till about 30 m from the finishing line. She then felt cramps in her legs but did not give up. She quickly took some deep and fast breaths and continued running. Her presence of mind, determination, courage and positive attitude, helped her to just manage to win the race. Rita and Neetu, who finished second and third, respectively, were the first to congratulate her on her success.
- State the values displayed by Shweta.
Answer – Determination, courage, presence of mind, and a positive attitude.
- Write about some situation in which you, or one of your friends, displayed a behaviour similar to that of Rita and Neetu.
Answer – (Example) When my friend forgot her lines during a school play, I encouraged her and helped her remember them. Later, I congratulated her for finishing it well.
- State the likely reason due to which Shweta felt cramps in her legs.
Answer – Cramps were caused by accumulation of lactic acid due to anaerobic respiration in muscles during heavy exertion.
Something To Do
- Observe the changes in a leaf when both of its surfaces are coated with oil/ vaseline? Perform this activity and give a simple explanation of your observations.
Answer – The leaf wilts and may eventually die because the coating blocks stomata, preventing gas exchange and transpiration.
- Find out about two diseases related to the respiratory system. List their causes, their effect on respiration and their cure.
Answer – Asthma: Caused by inflammation of airways; results in difficulty breathing. Treated with inhalers and medication.
Bronchitis: Caused by infection or irritants like smoke; leads to coughing and difficulty breathing. Treated with rest, fluids, and medicines.
- Record the breathing rates, of your friends and their family members (i) when at rest and (ii) after performing the activities given in the following table. Let the person rest for 15 minutes after performing each activity. Enter your results in the table given below:
S.No. | Name of the person | At rest (breaths/min) | After brisk walk for 10 minutes (breaths/min) | After skipping 100 times (breaths/min) |
1 | Rahul | 16 | 24 | 32 |
2 | Meena | 18 | 26 | 34 |
3 | Ankit | 15 | 23 | 30 |
4 | Riya | 17 | 25 | 33 |
Additional Questions and Answers – 01
Fill in the Blanks (with Answers)
- The breakdown of glucose in the presence of oxygen is called __________ respiration.
Answer: Aerobic - During anaerobic respiration in yeast, __________ is produced.
Answer: Alcohol - The process of breathing in humans is carried out by the __________ system.
Answer: Respiratory - During inspiration, the diaphragm moves __________.
Answer: Downward - The tiny air sacs in lungs are known as __________.
Answer: Alveoli - In plants, exchange of gases mainly takes place through __________.
Answer: Stomata - The exchange of gases in amoeba takes place through its __________.
Answer: Cell membrane - The windpipe is also known as the __________.
Answer: Trachea - Exhaled air contains more __________ and less oxygen.
Answer: Carbon dioxide - Fish breathe through __________.
Answer: Gills
Multiple Choice Questions (MCQs) (with Answers)
- Which of these is a product of anaerobic respiration in muscles?
a) Alcohol
b) Lactic acid
c) Oxygen
d) Carbon dioxide
Answer: b) Lactic acid - The respiratory pigment in human blood is—
a) Chlorophyll
b) Myoglobin
c) Haemoglobin
d) Keratin
Answer: c) Haemoglobin - Which of the following organisms breathes through moist skin?
a) Human
b) Frog
c) Cow
d) Parrot
Answer: b) Frog - Which gas is taken in during respiration?
a) Carbon dioxide
b) Nitrogen
c) Oxygen
d) Hydrogen
Answer: c) Oxygen - In humans, the air enters the lungs through—
a) Oesophagus
b) Bronchi
c) Windpipe
d) Nostrils and windpipe
Answer: d) Nostrils and windpipe
True / False Questions (with Answers)
- Anaerobic respiration occurs in the presence of oxygen.
False - Plants carry out only photosynthesis and not respiration.
False - The lungs are present in the abdominal cavity.
False - Carbon dioxide is a waste product of aerobic respiration.
True - The rate of breathing increases during exercise.
True - Stomata are found only on the upper surface of leaves.
False - Yeast respires anaerobically and produces alcohol.
True
Short Answer Questions
- What is anaerobic respiration?
Answer: Anaerobic respiration is the breakdown of food without the use of oxygen, producing less energy. - Why does the breathing rate increase during exercise?
Answer: To supply more oxygen to the muscles and remove carbon dioxide faster due to increased activity. - What are alveoli?
Answer: Alveoli are tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide occurs. - Mention two differences between aerobic and anaerobic respiration.
Answer:- Aerobic requires oxygen; anaerobic does not.
- Aerobic releases more energy; anaerobic releases less.
- What role does the diaphragm play in breathing?
Answer: The diaphragm contracts and moves downward during inhalation, increasing chest volume to draw air in.
Competency-Based (Reasoning & Assertion)
Assertion (A): The rate of breathing increases after running.
Reason (R): More oxygen is needed to convert lactic acid into carbon dioxide and water.
- a) Both A and R are true, and R is the correct explanation.
b) Both A and R are true, but R is not the correct explanation.
c) A is true, but R is false.
d) A is false, but R is true.
Answer: a) Both A and R are true, and R is the correct explanation.
Assertion (A): Yeast produces alcohol during anaerobic respiration.
Reason (R): Oxygen is required for yeast to produce alcohol.
- a) Both A and R are true, and R is the correct explanation.
b) Both A and R are true, but R is not the correct explanation.
c) A is true, but R is false.
d) A is false, but R is true.
Answer: c) A is true, but R is false.
High Order Thinking Skill (HOTS) Questions
- Why do mountaineers carry oxygen cylinders while climbing high mountains?
Answer: At high altitudes, the air pressure is low and oxygen is scarce. To avoid breathlessness and altitude sickness, mountaineers carry oxygen cylinders. - Why do fish die when taken out of water even though oxygen is present in the air?
Answer: Fish have gills that can extract dissolved oxygen from water, not from air. Outside water, their gills collapse and cannot function, leading to suffocation.
Long Answer Questions (50–60 words)
- Explain the process of aerobic respiration in humans.
Answer: In humans, aerobic respiration occurs in the presence of oxygen. Glucose from food is broken down into carbon dioxide and water, releasing energy. This energy is used by cells for various activities. The oxygen is transported to cells via blood, and the carbon dioxide produced is exhaled through the lungs.
- Describe how respiration takes place in insects.
Answer: Insects respire through a network of tubes called tracheae. Air enters the body through small openings called spiracles and reaches cells directly through tracheal tubes. This system provides oxygen directly to body tissues without involving blood for gas transport.
Additional Questions and Answers – 02
Fill in the Blanks Questions and Answers
- Question: Respiration converts ______ into biochemical energy using oxygen.
Answer: Respiration converts sugars into biochemical energy using oxygen. - Question: During respiration, carbon dioxide and ______ are produced as waste products.
Answer: During respiration, carbon dioxide and water are produced as waste products. - Question: In plants, ______ occurs simultaneously with respiration during the day.
Answer: In plants, photosynthesis occurs simultaneously with respiration during the day. - Question: At night, plants take in ______ and release carbon dioxide.
Answer: At night, plants take in oxygen and release carbon dioxide. - Question: Cellular respiration occurs in the ______ of the body.
Answer: Cellular respiration occurs in the cells of the body. - Question: Aerobic respiration releases energy from glucose in the presence of ______.
Answer: Aerobic respiration releases energy from glucose in the presence of oxygen. - Question: Anaerobic respiration takes place in the ______ of oxygen.
Answer: Anaerobic respiration takes place in the absence of oxygen. - Question: Anaerobic respiration in yeast is also called ______.
Answer: Anaerobic respiration in yeast is also called fermentation. - Question: Muscle cramps occur due to the accumulation of ______ acid during anaerobic respiration.
Answer: Muscle cramps occur due to the accumulation of lactic acid during anaerobic respiration. - Question: Plants exchange gases through small openings called ______ on their leaves.
Answer: Plants exchange gases through small openings called stomata on their leaves. - Question: The process of losing excess water through stomata in plants is called ______.
Answer: The process of losing excess water through stomata in plants is called transpiration. - Question: In small organisms like Amoeba, gas exchange occurs through ______.
Answer: In small organisms like Amoeba, gas exchange occurs through diffusion. - Question: Fish use ______ for respiration to extract oxygen from water.
Answer: Fish use gills for respiration to extract oxygen from water. - Question: Insects respire through a network of tubes called ______.
Answer: Insects respire through a network of tubes called tracheae. - Question: In humans, breathing involves ______ and exhalation.
Answer: In humans, breathing involves inhalation and exhalation. - Question: The ______ is a muscular partition that helps in human breathing.
Answer: The diaphragm is a muscular partition that helps in human breathing. - Question: An adult normally breathes ______ to 20 times per minute at rest.
Answer: An adult normally breathes 14 to 20 times per minute at rest. - Question: Haemoglobin in the blood transports ______ to different parts of the body.
Answer: Haemoglobin in the blood transports oxygen to different parts of the body. - Question: High levels of ______ dioxide in the body can be toxic.
Answer: High levels of carbon dioxide in the body can be toxic. - Question: Smoking damages the lungs due to chemicals like nicotine and ______.
Answer: Smoking damages the lungs due to chemicals like nicotine and tar.
Multiple Choice Questions and Answers
- Question: What is the primary purpose of respiration in living organisms?
a) To produce water
b) To release energy from food
c) To absorb oxygen
d) To remove glucose
Answer: b) To release energy from food - Question: What are the waste products of respiration?
a) Oxygen and glucose
b) Carbon dioxide and water
c) Nitrogen and water
d) Oxygen and carbon dioxide
Answer: b) Carbon dioxide and water - Question: During the day, plants perform both respiration and what other process?
a) Transpiration
b) Photosynthesis
c) Fermentation
d) Diffusion
Answer: b) Photosynthesis - Question: What happens in plants at night regarding respiration?
a) They take in carbon dioxide and release oxygen
b) They take in oxygen and release carbon dioxide
c) They stop respiring
d) They perform photosynthesis
Answer: b) They take in oxygen and release carbon dioxide - Question: Where does cellular respiration occur in the body?
a) Lungs
b) Cells
c) Blood
d) Heart
Answer: b) Cells - Question: What type of respiration requires oxygen?
a) Anaerobic
b) Aerobic
c) Fermentation
d) Diffusion
Answer: b) Aerobic - Question: What is anaerobic respiration in yeast also called?
a) Diffusion
b) Fermentation
c) Transpiration
d) Photosynthesis
Answer: b) Fermentation - Question: What causes muscle cramps during heavy exercise?
a) Accumulation of carbon dioxide
b) Accumulation of lactic acid
c) Lack of glucose
d) Excess oxygen
Answer: b) Accumulation of lactic acid - Question: How do plants exchange gases for respiration?
a) Through gills
b) Through stomata
c) Through tracheae
d) Through lungs
Answer: b) Through stomata - Question: What process in plants involves the loss of excess water through stomata?
a) Respiration
b) Photosynthesis
c) Transpiration
d) Fermentation
Answer: c) Transpiration - Question: How do small organisms like Amoeba exchange gases?
a) Through gills
b) Through diffusion
c) Through lungs
d) Through tracheae
Answer: b) Through diffusion - Question: What respiratory organ do fish use?
a) Lungs
b) Gills
c) Tracheae
d) Skin
Answer: b) Gills - Question: How do insects respire?
a) Through gills
b) Through lungs
c) Through tracheae
d) Through skin
Answer: c) Through tracheae - Question: What is inhalation in human breathing?
a) Taking in oxygen-rich air
b) Giving out carbon dioxide-rich air
c) Stopping breathing
d) Contracting the lungs
Answer: a) Taking in oxygen-rich air - Question: What helps in human breathing besides the rib cage?
a) Heart
b) Diaphragm
c) Liver
d) Kidneys
Answer: b) Diaphragm - Question: What is the normal breathing rate of an adult at rest?
a) 5 to 10 times per minute
b) 14 to 20 times per minute
c) 30 to 40 times per minute
d) 80 times per minute
Answer: b) 14 to 20 times per minute - Question: What transports oxygen in the human body?
a) Glucose
b) Haemoglobin
c) Carbon dioxide
d) Water
Answer: b) Haemoglobin - Question: Why do we need to exhale carbon dioxide?
a) It is needed for energy
b) High levels are toxic
c) It helps in breathing
d) It produces oxygen
Answer: b) High levels are toxic - Question: What harmful substance in cigarette smoke damages the lungs?
a) Oxygen
b) Glucose
c) Nicotine
d) Water
Answer: c) Nicotine - Question: What does the activity with germinating seeds show about respiration?
a) It produces carbon dioxide
b) It produces heat
c) It uses water
d) It stops in seeds
Answer: b) It produces heat
True/False Questions and Answers
- Question: Respiration releases energy from food in living organisms.
Answer: True - Question: Respiration produces oxygen as a waste product.
Answer: False (It produces carbon dioxide and water.) - Question: Plants perform photosynthesis at night along with respiration.
Answer: False (Photosynthesis stops at night.) - Question: At night, plants release oxygen and take in carbon dioxide.
Answer: False (They take in oxygen and release carbon dioxide.) - Question: Cellular respiration occurs in the lungs of the body.
Answer: False (It occurs in the cells.) - Question: Aerobic respiration requires oxygen to release energy.
Answer: True - Question: Anaerobic respiration in yeast is called fermentation.
Answer: True - Question: Muscle cramps are caused by the accumulation of glucose in muscles.
Answer: False (They are caused by lactic acid.) - Question: Plants exchange gases through stomata on their leaves.
Answer: True - Question: Transpiration is the process of energy release in plants.
Answer: False (It is the loss of excess water.) - Question: Small organisms like Amoeba use diffusion for gas exchange.
Answer: True - Question: Fish use lungs to extract oxygen from water.
Answer: False (They use gills.) - Question: Insects respire through a network of tracheae.
Answer: True - Question: Inhalation in humans is the process of taking in oxygen-rich air.
Answer: True - Question: The diaphragm in humans helps in breathing.
Answer: True - Question: An adult breathes 80 times per minute at rest.
Answer: False (It’s 14 to 20 times per minute.) - Question: Haemoglobin transports oxygen in the human body.
Answer: True - Question: High levels of carbon dioxide in the body are beneficial.
Answer: False (They are toxic.) - Question: Smoking damages the lungs due to chemicals like nicotine.
Answer: True - Question: Respiration in seeds produces a decrease in temperature.
Answer: False (It produces heat.)
Short Questions and Answers
- Question: What is the main purpose of respiration?
Answer: To release energy from food. - Question: What are the waste products of respiration?
Answer: Carbon dioxide and water. - Question: What process occurs in plants alongside respiration during the day?
Answer: Photosynthesis. - Question: What gases do plants exchange at night?
Answer: They take in oxygen and release carbon dioxide. - Question: Where does cellular respiration occur?
Answer: In the cells. - Question: What is aerobic respiration?
Answer: Releasing energy from glucose using oxygen. - Question: What is anaerobic respiration in yeast called?
Answer: Fermentation. - Question: What causes muscle cramps during exercise?
Answer: Accumulation of lactic acid. - Question: How do plants exchange gases?
Answer: Through stomata on their leaves. - Question: What is transpiration in plants?
Answer: Loss of excess water through stomata. - Question: How do Amoeba exchange gases?
Answer: Through diffusion. - Question: What respiratory organ do fish use?
Answer: Gills. - Question: How do insects respire?
Answer: Through tracheae. - Question: What is inhalation in human breathing?
Answer: Taking in oxygen-rich air. - Question: What muscle helps in human breathing?
Answer: Diaphragm. - Question: What is the normal breathing rate of an adult at rest?
Answer: 14 to 20 times per minute. - Question: What transports oxygen in the human body?
Answer: Haemoglobin. - Question: Why do we exhale carbon dioxide?
Answer: High levels are toxic. - Question: What harmful substance in cigarette smoke affects the lungs?
Answer: Nicotine. - Question: What does the germinating seeds activity show about respiration?
Answer: It produces heat.
Competency-Based Questions and Answers (Reasoning and Assertion)
- Question: Assertion (A): Plants release carbon dioxide at night.
Reason (R): Photosynthesis stops at night, and only respiration occurs.
Answer: Both A and R are true, and R is the correct explanation of A. At night, photosynthesis stops due to lack of light, as stated, and plants only respire, taking in oxygen and releasing carbon dioxide, explaining the net release of carbon dioxide during nighttime in plants. - Question: Assertion (A): Aerobic respiration is more efficient than anaerobic respiration.
Reason (R): Aerobic respiration uses oxygen to break down glucose completely.
Answer: Both A and R are true, and R is the correct explanation of A. Aerobic respiration, using oxygen, breaks down glucose fully, releasing more energy, as implied, while anaerobic respiration, like in muscles, produces less energy and lactic acid, making aerobic respiration more efficient for energy production in organisms. - Question: Assertion (A): Muscle cramps occur after heavy exercise.
Reason (R): Anaerobic respiration in muscles leads to lactic acid accumulation.
Answer: Both A and R are true, and R is the correct explanation of A. During heavy exercise, muscles respire anaerobically due to low oxygen, producing lactic acid, as noted, which accumulates and causes cramps, explaining why fatigue and cramps occur after intense physical activity in humans. - Question: Assertion (A): Plants can die if overwatered.
Reason (R): Overwatering fills soil air spaces with water, preventing root respiration.
Answer: Both A and R are true, and R is the correct explanation of A. Overwatering replaces air in soil spaces with water, as stated, depriving plant roots of oxygen needed for respiration, which can lead to root death and plant death, highlighting the importance of oxygen for plant survival. - Question: Assertion (A): Fish use gills for respiration.
Reason (R): Gills extract oxygen from water and release carbon dioxide.
Answer: Both A and R are true, and R is the correct explanation of A. Fish use gills to extract dissolved oxygen from water and release carbon dioxide, as described, enabling cellular respiration in an aquatic environment, making gills essential for their survival and gas exchange underwater. - Question: Assertion (A): Humans breathe faster after a sprint.
Reason (R): They need extra oxygen to break down accumulated lactic acid.
Answer: Both A and R are true, and R is the correct explanation of A. After a sprint, anaerobic respiration produces lactic acid, as noted, and faster breathing supplies extra oxygen to break it down, repaying the oxygen debt and restoring normal body conditions, explaining the increased breathing rate. - Question: Assertion (A): Stomata in plants help in gas exchange.
Reason (R): They allow oxygen and carbon dioxide to move in and out.
Answer: Both A and R are true, and R is the correct explanation of A. Stomata, as small openings on leaves, facilitate the exchange of oxygen and carbon dioxide during respiration and photosynthesis, as stated, enabling plants to maintain energy production and gas balance for survival. - Question: Assertion (A): Smoking damages the lungs.
Reason (R): Cigarette smoke contains chemicals like nicotine and tar.
Answer: Both A and R are true, and R is the correct explanation of A. Smoking introduces chemicals like nicotine and tar, as mentioned, which damage lung tissue, leading to breathing problems like cough and emphysema, explaining why smoking is a major cause of respiratory issues in humans. - Question: Assertion (A): Insects respire through tracheae.
Reason (R): Tracheae are a network of tubes that deliver oxygen directly to cells.
Answer: Both A and R are true, and R is the correct explanation of A. Insects use tracheae, a branched network opening through pores, as described, to deliver oxygen directly to cells and remove carbon dioxide, enabling efficient respiration without lungs in their small, high-metabolism bodies. - Question: Assertion (A): Haemoglobin is essential for human respiration.
Reason (R): It transports oxygen from the lungs to the body’s cells.
Answer: Both A and R are true, and R is the correct explanation of A. Haemoglobin, a red pigment in blood, as stated, carries oxygen from the lungs to cells for cellular respiration and returns carbon dioxide to the lungs, making it crucial for sustaining human life through respiration.
High Order Thinking Skills (HOTS) Questions and Answers
- Question: Why might plants release more carbon dioxide at night than during the day, and what does this suggest about the balance of respiration and photosynthesis?
Answer: At night, photosynthesis stops due to no light, so plants only respire, taking in oxygen and releasing carbon dioxide, unlike during the day when photosynthesis uses carbon dioxide. This suggests respiration and photosynthesis balance gas exchange—photosynthesis dominates in light, reducing net carbon dioxide release, showing their complementary roles in plant survival. - Question: How does anaerobic respiration in muscles affect athletic performance, and what does this indicate about the limitations of energy production in humans?
Answer: Anaerobic respiration in muscles during sprints produces lactic acid, causing cramps and fatigue, limiting performance over long distances, as it’s less efficient than aerobic respiration. This indicates human energy production has limitations—anaerobic respiration provides quick energy but cannot sustain prolonged activity, highlighting the need for oxygen to maximize efficiency in energy release. - Question: Why might overwatering kill a plant, and what does this reveal about the role of oxygen in plant survival?
Answer: Overwatering fills soil air spaces with water, preventing roots from accessing oxygen needed for respiration, leading to root death and plant death. This reveals oxygen is critical for plant survival—roots require it for cellular respiration to produce energy, showing that even plants, despite producing oxygen, depend on it for basic functions. - Question: How does the structure of fish gills enhance their respiratory efficiency, and what does this suggest about adaptations in aquatic environments?
Answer: Fish gills have filaments and lamellae with large surface areas, allowing efficient oxygen extraction from water and carbon dioxide release as water flows over them. This suggests aquatic adaptations optimize respiration—specialized structures like gills ensure survival in low-oxygen water, highlighting how environment drives the evolution of respiratory systems in aquatic organisms. - Question: Why might smaller animals have faster breathing rates than larger ones, and what does this indicate about metabolic rates in animals?
Answer: Smaller animals like rats breathe faster (60 times/minute) than larger ones like horses (12 times/minute) because they have higher metabolic rates, requiring more oxygen for energy. This indicates metabolic rates scale with size—smaller animals have faster metabolisms to support their high energy needs, necessitating quicker gas exchange through faster breathing for survival. - Question: How does the fermentation process in yeast benefit human industries, and what does this reveal about the practical applications of anaerobic respiration?
Answer: Fermentation in yeast produces alcohol and carbon dioxide, used in brewing beverages and baking bread, as the gas makes dough rise. This reveals anaerobic respiration has practical applications—industries exploit microbial respiration to create products, showing how biological processes can be harnessed for economic and culinary purposes beyond natural energy production. - Question: Why might smoking lead to severe respiratory diseases, and what does this suggest about the impact of environmental factors on respiration?
Answer: Smoking introduces chemicals like nicotine and tar, damaging lung tissue and airways, causing diseases like emphysema and cancer by impairing gas exchange. This suggests environmental factors significantly impact respiration—pollutants can disrupt normal lung function, highlighting the need for clean air to maintain healthy respiratory systems and overall well-being in humans. - Question: How does the diaphragm’s role in breathing demonstrate the complexity of human respiration, and what does this indicate about the integration of body systems?
Answer: The diaphragm contracts to expand the chest cavity during inhalation and relaxes during exhalation, working with the rib cage to facilitate breathing. This demonstrates the complexity of human respiration, indicating body systems like muscular and respiratory are integrated—coordinated movements ensure efficient gas exchange, essential for delivering oxygen and sustaining life processes. - Question: Why might yawning help regulate oxygen and carbon dioxide levels, and what does this reveal about the body’s response to respiratory imbalances?
Answer: Yawning brings in oxygen and removes excess carbon dioxide when levels rise due to drowsiness, as the brain triggers a deep breath to balance gases. This reveals the body’s sensitivity to respiratory imbalances—automatic responses like yawning maintain homeostasis, ensuring optimal oxygen and carbon dioxide levels for cellular function and overall health. - Question: How does transpiration in plants relate to their respiratory process, and what does this suggest about the interconnectedness of plant physiological processes?
Answer: Transpiration occurs through open stomata, which also facilitate gas exchange for respiration, linking water loss with oxygen intake and carbon dioxide release. This suggests plant processes are interconnected—stomata serve dual roles in respiration and water regulation, showing how plants integrate physiological functions to balance energy production, gas exchange, and water management for survival.
Long Questions and Answers (50-60 Words)
- Question: Describe the process of respiration in living organisms.
Answer: Respiration converts sugars into biochemical energy using oxygen, occurring in all organisms like animals and plants. It involves cellular respiration, where glucose breaks down in cells, producing energy, carbon dioxide, and water, as stated. This energy supports life processes, while gas exchange—oxygen intake and carbon dioxide release—ensures the body’s metabolic needs are met efficiently. - Question: Explain the difference between aerobic and anaerobic respiration.
Answer: Aerobic respiration releases energy from glucose using oxygen, producing carbon dioxide and water, as noted, while anaerobic respiration occurs without oxygen, producing less energy and byproducts like lactic acid in muscles or alcohol in yeast. Aerobic is more efficient, supporting sustained activity, whereas anaerobic, like fermentation, is used in low-oxygen conditions, such as during sprints or brewing. - Question: Discuss why muscle cramps occur after heavy exercise.
Answer: Muscle cramps occur after heavy exercise due to anaerobic respiration in muscles, which produces lactic acid when oxygen is scarce, as described. This acid accumulates, causing fatigue and cramps, as muscles cannot work efficiently. Post-exercise, faster breathing supplies oxygen to break down lactic acid, repaying the oxygen debt and relieving discomfort over time. - Question: Describe how plants exchange gases during respiration.
Answer: Plants exchange gases through stomata on leaves, which open during the day to take in oxygen and release carbon dioxide for respiration, as stated. Woody branches use lenticels, while roots access oxygen from soil air spaces. This diffusion-based process ensures cells get oxygen for energy production, supporting plant survival without specialized respiratory organs. - Question: Explain the role of haemoglobin in human respiration.
Answer: Haemoglobin, a red pigment in blood, transports oxygen from the lungs to body cells for cellular respiration, as noted, and carries carbon dioxide back to the lungs for exhalation. Acting as a respiratory carrier, haemoglobin ensures efficient gas exchange, maintaining energy production and removing toxic carbon dioxide, crucial for human survival and metabolic processes. - Question: Discuss the impact of smoking on the human respiratory system.
Answer: Smoking damages the lungs with chemicals like nicotine and tar, as mentioned, causing breathing problems from coughs to severe diseases like emphysema and cancer. These substances impair lung tissue and airways, reducing gas exchange efficiency, highlighting the severe impact of smoking on respiratory health and the importance of avoiding such harmful habits. - Question: Describe the mechanism of breathing in humans.
Answer: Breathing in humans involves inhalation and exhalation. During inhalation, the diaphragm contracts, expanding the chest cavity as ribs lift, lowering lung pressure, drawing in air, as described. During exhalation, the diaphragm relaxes, ribs return, and lungs contract, expelling air. This process, driven by the diaphragm and rib cage, ensures oxygen intake and carbon dioxide removal. - Question: Explain how fish use gills for respiration.
Answer: Fish use gills to respire by drawing water through their mouth, which flows over gill filaments and lamellae, as stated. Oxygen diffuses into the blood, while carbon dioxide exits into the water, expelled through gill openings. This efficient system allows fish to extract oxygen from water, supporting cellular respiration in their aquatic environment. - Question: Discuss the role of stomata in plant respiration and transpiration.
Answer: Stomata in plants facilitate respiration by allowing oxygen intake and carbon dioxide release, as noted, while also enabling transpiration, the loss of excess water, aiding the water cycle. Open during the day, stomata balance gas exchange and water regulation, showing their dual role in supporting plant energy production and maintaining hydration in varying conditions. - Question: Explain why smaller animals have faster breathing rates.
Answer: Smaller animals, like rats, breathe faster—about 60 times per minute—than larger ones, like horses at 12 times, due to higher metabolic rates, as stated. They need more oxygen to produce energy for their active metabolism, indicating that breathing rates reflect metabolic demands, ensuring sufficient oxygen for survival in smaller, high-energy animals.