Life Processes Section-1 (Nutrition & Respiration) - Class 10 MCQ

Respiration
- Respiration is the life process that converts chemical energy into heat energy.
- It is the process by which organisms release energy from food molecules and convert it into a form that can be used by cells.
- During respiration, glucose and oxygen are broken down to produce carbon dioxide, water, and energy in the form of ATP (adenosine triphosphate).
- The energy released during respiration is used for various cellular activities, such as muscle contraction, maintaining body temperature, and carrying out metabolic processes.
- Heat energy is a byproduct of respiration and is produced when the chemical bonds in glucose are broken.
- This heat energy helps to maintain the body temperature of organisms, especially in warm-blooded animals.
- Without respiration, organisms would not be able to convert the chemical energy stored in food into a usable form, resulting in a lack of energy for vital life processes.

Introduction:
In this question, we are asked to determine the simplest food among the given options: rice, wheat, butter, and glucose.
Analysis:
To determine the simplest food, we need to consider various factors such as composition, processing, and nutritional content.
Comparing the options:
1. Rice:
- Rice is a staple food and a primary source of carbohydrates.
- It is composed mainly of starch and contains small amounts of protein and fat.
- Rice is minimally processed and does not undergo extensive refining.
2. Wheat:
- Wheat is also a staple food and a rich source of carbohydrates.
- It contains more protein and fiber compared to rice.
- Wheat is processed to produce various food products such as flour, bread, and pasta.
3. Butter:
- Butter is a dairy product made from cream.
- It consists mainly of milk fat and a small amount of water.
- Butter undergoes processing to separate the fat from the cream.
4. Glucose:
- Glucose is a simple sugar and the primary source of energy for the body.
- It is a monosaccharide and the simplest form of sugar.
- Glucose is naturally present in various foods and is also used as a sweetener.
Conclusion:
Based on the analysis, the simplest food among the given options is glucose. It is a simple sugar and the most basic form of carbohydrate. Rice and wheat are complex carbohydrates, while butter is a dairy product consisting of fat and water.

Saprophytic mode of nutrition in organisms
- Saprophytic mode of nutrition refers to the ability of an organism to obtain nutrients by decomposing and absorbing organic matter from dead and decaying material.
- Organisms that exhibit saprophytic mode of nutrition play a crucial role in the decomposition and recycling of organic matter in ecosystems.
- Among the given options, the organism that has a saprophytic mode of nutrition is the Mushroom.
- Here is a detailed explanation of each option:
A. Mushroom:
- Mushrooms are fungi that obtain their nutrition by decomposing dead and decaying organic matter.
- They release enzymes that break down complex organic compounds into simpler forms, which are then absorbed by the mushroom.
B. Malarial parasite:
- Malarial parasites are not saprophytic organisms.
- They are parasitic organisms that obtain their nutrition by feeding on the host's blood.
C. Leech:
- Leeches are not saprophytic organisms.
- They are parasitic organisms that feed on the blood of their host.
D. Lice:
- Lice are not saprophytic organisms.
- They are parasitic organisms that feed on the blood of their host.
In conclusion, among the given options, the organism that exhibits a saprophytic mode of nutrition is the Mushroom.

Raw Materials for Photosynthesis:
- Carbon Dioxide: Carbon dioxide is one of the essential raw materials for photosynthesis. During the process of photosynthesis, plants take in carbon dioxide from the atmosphere through small pores called stomata in their leaves.
- Water: Water is another crucial raw material for photosynthesis. Plants absorb water from the soil through their roots and transport it to the leaves. In the leaves, water is used in the process of photosynthesis to provide hydrogen atoms for the synthesis of glucose.
- Oxygen: Although oxygen is released as a byproduct of photosynthesis, it is not considered a raw material for the process. Oxygen is produced when water molecules are split during the light-dependent reactions of photosynthesis. The released oxygen is then released into the atmosphere.
Conclusion:
Based on the given options, the correct answer is C: Oxygen. Oxygen is not a raw material for photosynthesis but rather a byproduct of the process. The primary raw materials for photosynthesis are carbon dioxide and water.

Answer:
The food is stored in the form of starch in leaves. Here is a detailed explanation:
- Starch: Starch is a complex carbohydrate made up of glucose molecules. It is the primary storage form of glucose in plants.
- Function: Starch serves as a reserve energy source in plants, allowing them to store excess glucose produced during photosynthesis for later use.
- Structure: Starch is composed of two components: amylose and amylopectin. Amylose is a linear chain of glucose molecules, while amylopectin is a branched chain.
- Location: Leaves contain specialized cells called chloroplasts that perform photosynthesis. Within the chloroplasts, starch granules are stored in the stroma, the fluid-filled region surrounding the thylakoid membranes.
- Conversion: When energy is needed, starch is broken down into glucose molecules by enzymes called amylases. The glucose is then transported to different parts of the plant for energy production or converted into other molecules as needed.
In conclusion, leaves store food in the form of starch, which serves as an energy reserve for plants.

The color of the iodine-starch complex is dark blue. Here is a detailed explanation of why iodine and starch form a dark blue complex:
1. Iodine:
- Iodine is a non-metallic element that exists as a diatomic molecule (I₂).
- It is a dark purple solid with a distinctive odor.
- Iodine is commonly used in chemistry as a reagent and indicator.
2. Starch:
- Starch is a complex carbohydrate made up of glucose units.
- It is a white, tasteless, and odorless powder.
- Starch is commonly found in plants and serves as their energy storage molecule.
3. Iodine-Starch Complex:
- When iodine comes into contact with starch, a chemical reaction occurs, resulting in the formation of a complex compound.
- The iodine molecules fit into the helical structure of starch, forming a complex that has a distinct color.
- The complex between iodine and starch is reversible and depends on the concentration of both substances.
- In the presence of iodine, starch turns into a dark blue or purplish-black color.
4. The Color:
- The dark blue color of the iodine-starch complex is due to the absorption of light in the visible spectrum.
- The complex absorbs light at specific wavelengths, resulting in the perception of a dark blue color.
- The intensity of the color depends on the concentration of iodine and starch present.
In conclusion, the color of the iodine-starch complex is dark blue. This reaction is commonly used to test for the presence of starch in various substances or to visualize the diffusion of iodine in experiments.

Answer:
The term for the process of taking food into the body is ingestion. Ingestion is the first step in the process of food processing in the human body. It involves the intake of food through the mouth.
Here is a detailed explanation of the process of ingestion:
Ingestion:
- Ingestion is the process of taking food into the body through the mouth.
- It involves the biting, chewing, and swallowing of food.
- The teeth break down the food into smaller pieces, and saliva helps in the lubrication and initiation of digestion.
- The tongue helps in the movement of food toward the back of the mouth and into the esophagus.
- The epiglottis prevents food from entering the windpipe and directs it to the esophagus.
Other processes involved in the digestion of food include:
- Digestion: The process of breaking down food into smaller molecules that can be absorbed by the body.
- Absorption: The process of absorbing the digested nutrients into the bloodstream.
- Assimilation: The process of incorporating the absorbed nutrients into the cells of the body.
It is important to note that while digestion, absorption, and assimilation are all crucial processes in the overall digestion and utilization of nutrients, the specific term for taking food into the body is ingestion.

The salivary gland secretes which of these enzymes?

• Amylase: The salivary gland secretes amylase, which is an enzyme that helps in the breakdown of carbohydrates into simpler sugars.


• Pepsin: Pepsin is not secreted by the salivary gland. It is produced in the stomach and helps in the digestion of proteins.


• Lipase: Lipase is not secreted by the salivary gland. It is produced by the pancreas and aids in the digestion of fats.


• Trypsin: Trypsin is not secreted by the salivary gland. It is produced in the pancreas and helps in the digestion of proteins.

Therefore, the correct answer is C: Amylase.

Respiration is a process in which:
- Energy is released and stored in the form of ATP:
- During respiration, glucose molecules are broken down in a series of chemical reactions.
- This breakdown process releases energy in the form of ATP (adenosine triphosphate).
- ATP is the primary energy currency of cells and is used to power various cellular processes.
- ADP is converted into ATP:
- ADP (adenosine diphosphate) is a molecule that is converted into ATP during respiration.
- This conversion occurs through the addition of a phosphate group to ADP, forming ATP.
- The release and storage of energy occur during this conversion process.
- Energy is used up:
- While energy is released and stored in the form of ATP during respiration, it does not mean that all energy is consumed or used up.
- The energy stored in ATP can be utilized by cells for various metabolic processes, such as muscle contraction, active transport, and synthesis of molecules.
- Energy is not released at all:
- This statement is incorrect as respiration is a process that involves the release and storage of energy.
- Without respiration, cells would not be able to generate ATP and carry out essential functions.
Therefore, the correct answer is C: Energy is released and stored in the form of ATP.

Organisms that can live without oxygen:
Amoeba, Sheep, Yeast, Leech
Detailed
- Amoeba:
- Amoebas are single-celled organisms that can live without oxygen.
- They can adapt to anaerobic environments where there is no air or oxygen present.
- They obtain energy through fermentation, breaking down glucose without the need for oxygen.
- Sheep:
- Sheep are unable to live without oxygen.
- They are mammals and require oxygen for respiration, just like humans.
- Yeast:
- Yeast can live without oxygen and can survive in both aerobic (with oxygen) and anaerobic (without oxygen) environments.
- In the absence of oxygen, yeast undergoes fermentation, converting sugar into alcohol and carbon dioxide to generate energy.
- Leech:
- Leeches are also unable to live without oxygen.
- They are aquatic organisms and require oxygen dissolved in water for respiration.
Conclusion:
Out of the given options, the organism that can live without oxygen is Yeast.

Haemoglobin is a type of respiratory pigment.
Explanation:
Haemoglobin is a protein found in red blood cells that is responsible for carrying oxygen from the lungs to other parts of the body. It plays a crucial role in the respiratory system and helps in the transportation of oxygen and carbon dioxide.
Here is a detailed explanation of why haemoglobin is classified as a respiratory pigment:
1. Function: Haemoglobin binds to oxygen in the lungs and forms oxyhemoglobin, which is then transported to the body tissues. It releases oxygen to the cells and picks up carbon dioxide, forming carbaminohemoglobin, which is transported back to the lungs for elimination.
2. Respiratory Pigment: Haemoglobin is classified as a respiratory pigment because it is directly involved in the transport of respiratory gases, such as oxygen and carbon dioxide, in the circulatory system. It has a high affinity for oxygen, allowing it to efficiently carry oxygen molecules.
3. Structure: Haemoglobin consists of four subunits, each containing a heme group. The heme group contains an iron molecule, which binds to oxygen and gives haemoglobin its characteristic red color. This iron-oxygen binding allows for efficient oxygen transport.
4. Oxygen Affinity: Haemoglobin's affinity for oxygen is influenced by factors such as pH, temperature, and carbon dioxide levels. This allows it to adjust its oxygen-binding capacity based on the needs of different tissues and organs.
5. Other Respiratory Pigments: Apart from haemoglobin, there are other respiratory pigments found in different organisms. Examples include myoglobin in muscles and hemocyanin in some invertebrates. These pigments also play a role in oxygen transport and storage.
In conclusion, haemoglobin is classified as a respiratory pigment due to its crucial role in the transport of oxygen and carbon dioxide in the circulatory system. Its ability to bind and release oxygen efficiently makes it essential for proper respiratory function.

Explanation:
When air is blown into a test tube containing lime water, the lime water turns milky due to the presence of carbon dioxide (CO2) in the exhaled breath. This chemical reaction can be explained as follows:
1. Carbon Dioxide Reacts with Calcium Hydroxide:
- Lime water is a solution of calcium hydroxide (Ca(OH)2) in water.
- When carbon dioxide gas is blown into the lime water, it reacts with the calcium hydroxide to form calcium carbonate (CaCO3).
- The chemical equation for this reaction is: CO2 + Ca(OH)2 -> CaCO3 + H2O
2. Formation of Calcium Carbonate Precipitate:
- The calcium carbonate formed during the reaction is insoluble in water.
- As a result, it appears as a white precipitate, making the lime water turn milky in appearance.
3. Lime Water as a Carbon Dioxide Indicator:
- Lime water is commonly used as a test for the presence of carbon dioxide gas.
- The reaction between carbon dioxide and lime water is a simple and effective way to detect the presence of carbon dioxide.
- The formation of the milky precipitate confirms the presence of carbon dioxide in the exhaled breath.
Therefore, the correct answer is D: Carbon-Dioxide.

During expiration, the intercostal muscles and the diaphragm are relaxed leading to decrease in the volume of the thoracic cavity so that the air is expired from the lungs. The relaxed diaphragm gets arched up forming a dome.

Xylem in plants:
The xylem in plants plays a crucial role in the transportation of water and minerals from the roots to the rest of the plant. Here is a detailed explanation of its function:
1. Transport of water:
- The primary function of xylem is to transport water and dissolved minerals from the roots to the leaves and other parts of the plant.
- Water is absorbed from the soil by the roots through root hairs and is transported upwards through the xylem vessels.
- This upward movement of water is achieved through a combination of capillary action, cohesion, and transpiration pull.
2. Transport of minerals:
- Along with water, xylem also transports essential minerals and nutrients that are absorbed by the roots.
- These minerals are dissolved in the water and are transported via the xylem vessels to the different parts of the plant where they are needed for various metabolic processes.
3. Water balance and support:
- Xylem also helps in maintaining the water balance in the plant by regulating the movement of water between different plant tissues.
- The structural components of xylem, such as the tracheids and vessel elements, provide strength and support to the plant, allowing it to withstand the forces of gravity and wind.
In conclusion, the xylem in plants is primarily responsible for the transport of water and minerals from the roots to the rest of the plant. It plays a vital role in maintaining the water balance, providing support, and supplying essential nutrients for the overall growth and survival of the plant.

The autotrophic mode of nutrition requires:
- Carbon dioxide and water: Autotrophs, such as plants, use carbon dioxide from the atmosphere and water from the soil to carry out photosynthesis, which is the process by which they produce glucose and oxygen.
- Chlorophyll: Chlorophyll is a pigment found in the chloroplasts of plant cells. It is responsible for absorbing light energy from the sun, which is then used in the process of photosynthesis. Chlorophyll gives plants their green color.
- Sunlight: Sunlight is the source of energy for autotrophs. It provides the light energy needed for photosynthesis to occur. The energy from sunlight is used to convert carbon dioxide and water into glucose and oxygen.
- All of the above: All the mentioned factors - carbon dioxide, water, chlorophyll, and sunlight - are necessary for autotrophs to carry out photosynthesis and produce their own food.
In conclusion, the autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll, and sunlight. These factors work together in the process of photosynthesis, allowing autotrophs to produce glucose and oxygen, which serves as their source of energy and sustenance.