Olympiad Test: Transport And Excretion -1 - Class 7 MCQ

The heart is the organ of the circulatory system that pumps blood.
- The circulatory system is responsible for transporting blood, nutrients, and oxygen throughout the body.
- The heart is a muscular organ located in the chest and is considered the central pump of the circulatory system.
- It consists of four chambers: two atria and two ventricles.
- The atria receive blood from the veins, while the ventricles pump blood out of the heart.
- The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs for oxygenation.
- The left side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body.
- The heart contracts and relaxes rhythmically, allowing it to pump blood efficiently and maintain blood flow throughout the body.
- The heartbeat is controlled by electrical signals that originate in the sinoatrial (SA) node, also known as the natural pacemaker of the heart.
- The SA node sends signals to the atria, causing them to contract and push blood into the ventricles.
- The signals then travel to the atrioventricular (AV) node, which relays the signals to the ventricles, causing them to contract and pump blood out of the heart.
- The continuous pumping action of the heart keeps the blood circulating through the blood vessels, supplying oxygen and nutrients to the body's cells and removing waste products.

The solution of minerals, water, food, and gases that is circulated through xylem and phloem is called sap. It plays a crucial role in the transportation of nutrients and other essential substances throughout the plant. Here is a detailed explanation of sap:
1. Definition:
- Sap is a fluid that contains a mixture of water, minerals, sugars, hormones, and other nutrients.
- It is the vital circulatory fluid in plants, responsible for transporting these substances between different parts of the plant.
2. Circulation:
- Sap is transported through two types of vascular tissues: xylem and phloem.
- Xylem is responsible for the upward movement of water and minerals from the roots to the leaves.
- Phloem, on the other hand, transports sugars, amino acids, hormones, and other organic molecules in both directions, allowing for bidirectional movement of sap.
3. Composition:
- Sap primarily consists of water, which serves as a medium for transporting nutrients.
- It also contains minerals such as potassium, calcium, and magnesium, which are essential for plant growth.
- Sugars, particularly sucrose, are another major component of sap, providing energy for the plant's metabolic processes.
4. Functions:
- Sap plays a vital role in photosynthesis, as it carries water and minerals to the leaves where photosynthesis occurs.
- It also transports the sugars produced during photosynthesis to various parts of the plant, providing energy for growth and development.
- Sap helps in the distribution of hormones, signaling molecules, and defense compounds, allowing for communication and protection within the plant.
In conclusion, sap is the solution of minerals, water, food, and gases that is circulated through xylem and phloem in plants. It is essential for the transportation of nutrients and plays a crucial role in the growth and development of plants.

The water and minerals absorbed by the roots of a plant move upwards to the other parts of the plant through the xylem. Here is a detailed explanation of this process:
Xylem:
- The xylem is a specialized tissue in plants that is responsible for the transport of water, minerals, and nutrients from the roots to the other parts of the plant.
- It is composed of long, hollow, and tube-like cells called tracheary elements, which are dead at maturity.
- The tracheary elements include two types of cells: the vessel elements and the tracheids.
- Vessel elements are found in angiosperms (flowering plants) and are arranged end to end to form long tubes.
- Tracheids are found in gymnosperms (non-flowering plants) and are more primitive in structure compared to vessel elements.
Process of Water and Mineral Transport:
- Water and minerals are absorbed by the roots through root hairs, which are located on the surface of the root.
- These substances enter the root cells through osmosis and active transport.
- Once inside the root cells, water and minerals are transported across the root cortex towards the xylem.
- The movement of water and minerals from cell to cell within the root is facilitated by specialized structures called plasmodesmata.
- Once in the xylem, water and minerals are transported upwards through the plant, primarily through the process of transpiration.
Transpiration:
- Transpiration is the loss of water vapor from the aerial parts of the plant, mainly through the stomata present on the leaves.
- As water evaporates from the leaf surface, it creates a negative pressure or tension within the xylem.
- This negative pressure pulls water from the roots, creating a continuous flow of water and minerals upwards through the xylem.
- This process is known as the cohesion-tension theory.
- The movement of water and minerals through the xylem is unidirectional and occurs from the roots to the shoots.
In conclusion, the solution of water and minerals absorbed by the roots moves upwards to the other parts of the plant through the xylem. This transport is facilitated by the process of transpiration and the cohesion-tension theory.

Which material is not a waste in man?
The material that is not a waste in man is glucose.
Explanation:
Glucose is a simple sugar that is an essential source of energy for the human body. It is derived from the breakdown of carbohydrates and is used by cells for various metabolic processes. Unlike the other options mentioned, glucose is not considered a waste product in the human body.
Let's examine the other options:
Urea:
- Urea is a waste product formed in the liver from the breakdown of proteins. It is then excreted by the kidneys in urine.
Carbon dioxide:
- Carbon dioxide is produced as a waste product during cellular respiration. It is transported through the bloodstream to the lungs, where it is exhaled.
Water:
- Water is not considered a waste product in the human body. It is essential for various physiological processes and is involved in maintaining hydration, regulating body temperature, and facilitating nutrient absorption and waste excretion.
In summary, glucose is the material that is not considered a waste in the human body. It is a vital source of energy and is used by cells for various metabolic functions.

Kidneys are located in the abdomen
The kidneys are important organs in the human body that play a crucial role in filtering waste products from the blood and regulating fluid balance. They are located in the abdomen, specifically in the retroperitoneal space, which is behind the peritoneum (the lining of the abdominal cavity).
Here are some key points about the location of the kidneys:
- The kidneys are bean-shaped organs that are approximately the size of a fist.
- They are situated on either side of the spine, just below the ribcage.
- The right kidney is slightly lower than the left kidney due to the position of the liver.
- The kidneys are protected by layers of fat and the ribcage, which helps cushion them from injury.
- The kidneys are connected to the bladder by two tubes called ureters, which transport urine from the kidneys to the bladder for storage and elimination.
In conclusion, the kidneys are located in the abdomen, specifically in the retroperitoneal space.

Capillaries have no muscular wall. They have thin walls hence diffusion or exchange of gases takes place in capillaries easily. 

Transpiration means the loss of water and waste materials through stomata and lenticels. 

Glucose solution when treated with Benedict's solution and heated turns
- When glucose solution is treated with Benedict's solution and heated, it undergoes a chemical reaction known as the Benedict's test.
- The Benedict's test is used to detect the presence of reducing sugars, such as glucose, in a solution.
- Benedict's solution contains copper sulfate, which is blue in color, and when reducing sugars are present, they can reduce the copper sulfate to form a precipitate.
- The color change observed during the Benedict's test can indicate the concentration of reducing sugars present in the solution.
- In the case of glucose solution, when treated with Benedict's solution and heated, it turns from blue to red.
- The red color indicates a positive result for the presence of reducing sugars, specifically glucose, in the solution.
- This color change occurs due to the reduction of copper sulfate by the glucose molecules present in the solution.
- The formation of the red precipitate confirms the presence of glucose in the solution.
- Therefore, the correct answer is B: red.

The upper chambers of the heart are called auricles.
- The heart is divided into four chambers: two upper chambers and two lower chambers.
- The upper chambers are called auricles, also known as atria.
- The auricles receive blood returning to the heart from the body and lungs.
- They are responsible for contracting to push the blood into the lower chambers of the heart.
- The lower chambers of the heart are called ventricles.
- The ventricles then pump the blood out of the heart to the rest of the body.
- The auricles and ventricles work together to maintain the circulation of blood throughout the body.
- The auricles have thinner walls compared to the ventricles, as their main function is to receive and store blood rather than pump it.
- The auricles are located superiorly in the heart, while the ventricles are located inferiorly.
- The auricles and ventricles are separated by the atrioventricular valves, which prevent backflow of blood between the chambers.
In summary, the upper chambers of the heart are called auricles or atria, and their main function is to receive blood and pump it into the lower chambers, known as ventricles.

The lower chambers of the heart are called ventricles.

The ventricles are the two lower chambers of the heart that are responsible for pumping blood to the rest of the body. They are larger and more muscular than the upper chambers of the heart, known as the atria.

Here are some key points about the ventricles:

• Location: The ventricles are located in the lower part of the heart, below the atria.


• Function: They receive blood from the atria and pump it out to the lungs and the rest of the body.


• Left Ventricle: The left ventricle is responsible for pumping oxygenated blood to the body's organs and tissues.


• Right Ventricle: The right ventricle pumps deoxygenated blood to the lungs to pick up oxygen.


• Valves: The ventricles are separated from the atria by valves, which ensure that blood flows in one direction.


• Contractions: The ventricles contract forcefully to pump blood out of the heart, creating the pulse.


• Blood Supply: The ventricles receive blood supply from the coronary arteries, which provide oxygen and nutrients to the heart muscle.

Overall, the ventricles play a crucial role in the circulatory system by pumping blood efficiently to meet the body's oxygen and nutrient needs.

The correct answer is C: Right ventricle.
Explanation:
The heart is a vital organ responsible for pumping blood throughout the body. It consists of four chambers: two atria (auricles) and two ventricles. In the process of circulation, deoxygenated blood is pumped to the lungs to receive oxygen, and oxygenated blood is then pumped to the rest of the body.
Here is a detailed explanation of the process:
1. Right atrium (auricle): Deoxygenated blood from the body enters the heart through the superior and inferior vena cava and is collected in the right atrium.
2. Right ventricle: From the right atrium, the blood flows into the right ventricle. The right ventricle is responsible for pumping deoxygenated blood to the lungs.
3. Pulmonary artery: From the right ventricle, the deoxygenated blood is pumped through the pulmonary artery, which carries it to the lungs.
4. Lungs: In the lungs, the blood picks up oxygen and releases carbon dioxide through the process of respiration.
5. Pulmonary veins: The oxygenated blood then returns to the heart through the pulmonary veins.
6. Left atrium (auricle): The oxygenated blood enters the left atrium from the pulmonary veins.
7. Left ventricle: From the left atrium, the blood flows into the left ventricle. The left ventricle is responsible for pumping oxygenated blood to the rest of the body.
It is important to note that the left side of the heart (left atrium and left ventricle) pumps oxygenated blood to the body, while the right side of the heart (right atrium and right ventricle) pumps deoxygenated blood to the lungs.
Therefore, the correct answer is C: Right ventricle, as it pumps deoxygenated blood to the lungs.

Answer:
The correct answer is A: left auricle. Here is a detailed explanation:

• Heart anatomy: To understand which structure receives oxygenated blood from the lungs, we need to have a basic understanding of the anatomy of the heart.


• Auricles: The auricles are two small, ear-shaped extensions on the top of the heart. They are also called atria.


• Left auricle: The left auricle, also known as the left atrium, receives oxygenated blood from the lungs through the pulmonary veins.


• Pulmonary veins: The pulmonary veins are the blood vessels that carry oxygenated blood from the lungs to the heart.


• Oxygenated blood: Since the left auricle receives oxygenated blood from the lungs, it is responsible for pumping this oxygen-rich blood to the rest of the body.

Therefore, the correct answer is A: left auricle, as it receives oxygenated blood from the lungs through the pulmonary veins.

Statement A:
- Oxygenated blood is pumped to all other parts of the body from the left ventricle.
- This statement is true.
- The left ventricle is responsible for pumping oxygen-rich blood to the rest of the body through the systemic circulation.
Statement B:
- Blood from the right side of the heart enters into the left side through the right auricle and left auricle.
- This statement is false.
- Blood from the right side of the heart enters the left side through the left atrium, not the right auricle and left auricle.
- The right auricle and left auricle are chambers that receive blood from the veins and pass it to the ventricles.
Statement C:
- Gaseous exchange in the alveoli happens through capillaries.
- This statement is true.
- The alveoli in the lungs are surrounded by a network of capillaries.
- Oxygen from the inhaled air diffuses across the thin walls of the alveoli and into the capillaries, while carbon dioxide diffuses from the capillaries into the alveoli for exhalation.
Statement D:
- Lungs oxygenate the deoxygenated blood.
- This statement is true.
- Deoxygenated blood from the body enters the lungs through the pulmonary arteries.
- In the lungs, carbon dioxide is removed from the blood, and oxygen is added through the process of respiration, resulting in oxygenated blood that is then returned to the heart.
Therefore, the false statement is B: Blood from the right side of the heart enters into the left side through the right auricle and left auricle.

Root hair of root of a plant absorbs:
The root hairs of a plant play a crucial role in the absorption of water and nutrients from the soil. They are thin, elongated structures that increase the surface area of the roots, allowing for more efficient absorption. Here is a detailed explanation of what root hairs absorb:
1. Water:
- The primary function of root hairs is to absorb water from the soil.
- Water is essential for plant growth and is transported from the roots to the rest of the plant through the xylem vessels.
2. Oxygen:
- While root hairs do not directly absorb oxygen, they create an environment in the soil that allows oxygen to enter the roots.
- Oxygen is necessary for cellular respiration in the roots and helps in the production of energy for the plant.
3. Salts:
- Root hairs also absorb various salts, including mineral nutrients, from the soil.
- These salts, such as nitrogen, phosphorus, and potassium, are essential for plant growth and development.
4. All of these:
- The correct answer to the given question is option D, which states that root hairs absorb water, oxygen, and salts.
- Root hairs have specialized structures and transport mechanisms that enable them to take up all of these substances.
In summary, root hairs of a plant primarily absorb water, oxygen, and salts from the soil. These substances are essential for the plant's survival and growth.