Olympiad Test: Respiration In Organisms -2 - Class 7 MCQ

Explanation:
Unicellular organisms are single-celled organisms that carry out all their life processes within a single cell. They do not have specialized organs or systems like multicellular organisms. In these organisms, oxygen is obtained and utilized in a simple and direct manner.
In most unicellular organisms:
- Oxygen is diffused into the cell directly from the surrounding environment. This process occurs through the cell membrane, which allows gases, including oxygen, to pass through.
- The oxygen molecules move from an area of higher concentration (the environment) to an area of lower concentration (inside the cell) through the process of diffusion.
- The cell membrane is thin and permeable, allowing oxygen to easily pass through and reach the organelles within the cell where it is utilized for cellular respiration.
- This diffusion of oxygen into the cell is a passive process and does not require any specialized organs or structures.
Therefore, the correct answer is:
C: Oxygen is diffused into the cell.

The correct answer is Anaerobic respiration.

• Alcohol is produced during the process of fermentation.
• Alcohol is the end product of fermentation.
• In alcoholic fermentation, pyruvate from glycolysis is converted to acetaldehyde and then to ethanol and carbon dioxide.
• Fermentation is the process of energy production in the absence of oxygen i.e anaerobic respiration.
• The process of energy production in the presence of oxygen is known as Aerobic respiration.
• Photosynthesis is the process by which green plants or phototrophs transform light energy into chemical energy. 

The diaphragm forms the floor of the chest cavity.
The chest cavity, also known as the thoracic cavity, is a hollow space within the chest that houses the lungs, heart, and other vital organs. The diaphragm is a dome-shaped muscle that separates the chest cavity from the abdominal cavity. It plays a crucial role in the process of breathing.
Here is a detailed explanation of why the diaphragm forms the floor of the chest cavity:
1. Anatomy of the diaphragm:
- The diaphragm is a thin, sheet-like muscle that extends across the bottom of the ribcage.
- It attaches to the inner surface of the lower ribs, sternum, and spine.
- The central portion of the diaphragm is thicker and forms a dome shape when relaxed.
2. Function of the diaphragm:
- The main function of the diaphragm is to aid in breathing.
- When the diaphragm contracts, it moves downward, increasing the volume of the chest cavity.
- This downward movement of the diaphragm creates negative pressure within the lungs, allowing air to be drawn into the lungs during inhalation.
- When the diaphragm relaxes, it moves back up, decreasing the volume of the chest cavity and causing exhalation.
3. Position within the chest cavity:
- The diaphragm is positioned horizontally, separating the thoracic cavity from the abdominal cavity.
- It forms the floor of the chest cavity, while the lungs and other thoracic organs lie above it.
- The pleural membranes, which surround the lungs and line the chest cavity, are located on the sides of the chest cavity.
In conclusion, the diaphragm forms the floor of the chest cavity and plays a vital role in the process of breathing.

Explanation:
When we exhale air into lime water, a chemical reaction occurs between the carbon dioxide in our breath and the calcium hydroxide in the lime water. This reaction produces a white precipitate called calcium carbonate.
The lime water changes from clear to milky because of the formation of the calcium carbonate precipitate. This is the result of the following reaction:
CO2 (carbon dioxide) + Ca(OH)2 (calcium hydroxide) → CaCO3 (calcium carbonate) + H2O (water)
The calcium carbonate is insoluble in water and forms a milky suspension in the lime water. This is a visual indicator that carbon dioxide is present in our breath.
So, the correct answer is B: "turns to milky."

Fishes use a specialized organ called gills to breathe. They use the oxygen dissolved in water. Some animals which live on land have skin which is so thin that gases can easily pass through it. For example, Earthworms and amphibians have a skin which is permeable to gases. Earthworms do not have lungs and breathe only through their skin. Most amphibians breathe through both skin and lungs. The frog is an amphibian. So, the answer is c.

Fishes and their respiratory organs
Introduction:
Fishes, being aquatic organisms, require specialized respiratory organs to extract oxygen from water. Gills are the primary respiratory organs in fishes, allowing them to respire in their aquatic environment.
Gills:
Gills are specialized organs that are responsible for extracting oxygen from water and removing carbon dioxide. They are located on the sides of fishes' heads, protected within gill chambers.
Origin of gills:
Gills are not projections of the skin, nostrils, or the alimentary canal. They have a different origin and are developed from the pharyngeal arches in fishes.
Function of gills:
Gills perform the following functions in fishes:
1. Oxygen uptake: Gills extract dissolved oxygen from water, which is then transported to the fish's bloodstream for distribution to the body tissues.
2. Carbon dioxide release: Gills eliminate carbon dioxide, a waste product of cellular respiration, by diffusing it out into the surrounding water.
3. Ion regulation: Gills also play a role in regulating the balance of ions such as sodium, chloride, and calcium in the fish's body.
4. Acid-base balance: Gills help maintain the pH balance of the fish's body fluids by regulating the levels of bicarbonate ions.
5. Osmoregulation: Gills assist in maintaining the proper balance of water and salts in the fish's body, allowing them to live in various aquatic environments.
Conclusion:
Gills are the respiratory organs in fishes, responsible for extracting oxygen from water and removing carbon dioxide. They are not projections of the skin, nostrils, or the alimentary canal. Understanding the structure and function of gills is crucial in studying the respiratory adaptations of fishes to their aquatic habitat.

Statement Analysis:

A: taking in of oxygen is inhalation

B: taking in of carbon dioxide is inhalation

C: giving out of carbon dioxide is exhalation

D: breathing rate is number of inhalation and exhalation in one minute.

Let's analyze each statement to determine which one is not correct:

• Statement A: taking in of oxygen is inhalation - This statement is correct. Inhalation refers to the process of breathing in oxygen.


• Statement B: taking in of carbon dioxide is inhalation - This statement is not correct. Inhalation is the process of breathing in oxygen, not carbon dioxide. Breathing out carbon dioxide is called exhalation.


• Statement C: giving out of carbon dioxide is exhalation - This statement is correct. Exhalation refers to the process of breathing out carbon dioxide.


• Statement D: breathing rate is number of inhalation and exhalation in one minute - This statement is correct. Breathing rate is typically measured by counting the number of inhalations and exhalations in one minute.

Therefore, the correct answer is Statement B: taking in of carbon dioxide is inhalation.

The function of hair follicles inside the nose is to trap germs and dust particles in the air.
The nose plays a crucial role in the respiratory system, and the hair follicles inside the nose, known as nasal hairs or cilia, serve an important function in filtering the air we breathe. Here's a detailed explanation of how hair follicles inside the nose function to trap germs and dust particles in the air:
1. Nasal Hair Structure:
- The nose is lined with a layer of mucus that helps to moisturize the air and trap particles.
- Hair follicles, or nasal hairs, are present in the nostrils and nasal passages.
- These hairs are coated with a layer of mucus, which helps to capture and hold onto particles present in the air.
2. Filtration Process:
- When we inhale, the air enters the nasal passages and passes over the nasal hairs.
- As the air flows through, the nasal hairs act as a physical barrier, trapping larger particles such as dust, pollen, and germs.
- The mucus coating on the hairs helps to capture and hold onto these trapped particles.
3. Protection and Prevention of Infections:
- The function of the nasal hairs is to prevent harmful particles, such as germs and dust, from entering the respiratory system.
- By trapping these particles, the nasal hairs help to prevent them from reaching the lungs, where they could cause infections or respiratory issues.
- The mucus coating on the nasal hairs also plays a role in preventing the particles from reaching the lungs by capturing and neutralizing them.
4. Importance for Overall Health:
- The hair follicles inside the nose are essential for maintaining good respiratory health.
- By filtering the air we breathe, they help to reduce the number of harmful particles that enter our lungs.
- This function is particularly important in environments with high levels of pollutants, allergens, or infectious agents.
In conclusion, the primary function of the hair follicles inside the nose is to trap germs and dust particles in the air we breathe. By doing so, they help to protect our respiratory system from potential infections and maintain good overall health.

Answer:
The correct answer is option A: palate. The nasal and oral cavities in humans are separated by the palate, which is a structure made up of bone and soft tissue. The palate is located in the roof of the mouth and it has two parts: the hard palate and the soft palate.
- Hard palate: The front part of the palate is called the hard palate. It is made up of bone and forms a rigid structure that separates the nasal and oral cavities.
- Soft palate: The back part of the palate is called the soft palate. It is made up of soft tissue and is more flexible compared to the hard palate. The soft palate extends beyond the hard palate and hangs down towards the back of the throat.
The palate plays an important role in the process of swallowing and speech production. It helps to separate the airflow between the nose and mouth, allowing us to breathe through the nose and also preventing food and liquid from entering the nasal cavity during swallowing.
In summary, the nasal and oral cavities in humans are separated by the palate, specifically the hard palate and the soft palate.