Science Form 3 Chapte 1-2

The correct answer is B. Inhalation refers to the process of breathing in air. This involves the intake of oxygen into the lungs and the exchange of gases, where oxygen is absorbed into the bloodstream and carbon dioxide is released. Inhalation is an essential process for respiration and providing oxygen to the body's cells.

Human blood consists of red blood cells, white blood cells, and platelets. These components are essential for various functions in the body. Red blood cells carry oxygen to different parts of the body, white blood cells are involved in the immune response and help fight against infections, and platelets are responsible for blood clotting to prevent excessive bleeding. These three components work together to maintain the overall health and functioning of the body's circulatory system.

Gaseous exchange takes place in the alveoli. The alveoli are tiny air sacs located in the lungs where oxygen from the inhaled air diffuses into the bloodstream and carbon dioxide, a waste product, diffuses out of the bloodstream into the alveoli to be exhaled. This process allows for the exchange of gases between the lungs and the bloodstream, ensuring that oxygen is delivered to the body's tissues and carbon dioxide is removed. The stomach and intestine are not involved in gaseous exchange.

The pulmonary artery carries deoxygenated blood from the heart to the lungs. After the blood is pumped out of the right ventricle of the heart, it enters the pulmonary artery and is then transported to the lungs where it picks up oxygen and gets rid of carbon dioxide. Once the blood is oxygenated, it returns to the heart through the pulmonary veins. Therefore, the correct answer is B. pulmonary.

During inhalation, the ribs move upwards and outwards. This is because the diaphragm, the main muscle involved in inhalation, contracts and moves downwards, causing the chest cavity to expand. As a result, the ribcage is pulled upwards and outwards, allowing more space for the lungs to expand and fill with air. This movement of the ribs helps in increasing the volume of the thoracic cavity, creating a pressure gradient that allows air to flow into the lungs.

Blood capillaries are the smallest blood vessels in the body and they play a crucial role in the exchange of oxygen, nutrients, and waste products between the blood and surrounding tissues. They are composed of a single layer of endothelial cells, which are one-cell thick. This thin layer allows for efficient diffusion of substances through the capillary walls, ensuring that oxygen and nutrients can reach the tissues and waste products can be removed. Therefore, option C is the correct answer.

When blood is oxygenated, it becomes bright red in color. Oxygen-rich blood is pumped from the lungs to the rest of the body, and this oxygenation process gives the blood its bright red hue.

When haemoglobin combines with oxygen, it forms oxyhaemoglobin. This compound is essential for the transportation of oxygen throughout the body. Oxyhaemoglobin is formed in the lungs when oxygen binds to the iron atoms present in haemoglobin. It then carries the oxygen to the tissues and releases it where it is needed. This process is crucial for the delivery of oxygen to cells and organs, ensuring their proper functioning.

Xylem is a type of plant tissue responsible for transporting water from the roots to the rest of the plant. It consists of specialized cells called tracheids and vessel elements that form long tubes for water movement. These cells are interconnected and have small openings called pits, allowing water to flow through. Xylem plays a crucial role in supplying water to the leaves for photosynthesis and providing structural support to the plant. Therefore, the statement "Xylem transports water" is true.

Arteries carry blood away from the heart to the rest of the body. They are thick-walled and elastic, allowing them to withstand the high pressure generated by the pumping action of the heart. This high pressure is necessary to ensure that oxygenated blood reaches all the tissues and organs efficiently. Therefore, the correct answer is A. high.

Phloem is a specialized tissue in plants that transports food, such as sugars and nutrients, from the leaves to the roots. It is responsible for the downward movement of these substances through a process called translocation. The phloem consists of sieve tubes and companion cells, which work together to facilitate the movement of food molecules. This transportation system is essential for distributing the products of photosynthesis to all parts of the plant, ensuring its growth and survival.

The statement is false because there are actually two types of blood circulation - systemic circulation and pulmonary circulation. Systemic circulation carries oxygenated blood from the heart to the body's tissues and organs, while pulmonary circulation carries deoxygenated blood from the heart to the lungs for oxygenation.

Diffusion is the process where gas molecules move from a place where there are many molecules to a place with fewer molecules. This occurs due to the random motion of molecules and the tendency for them to spread out and fill the available space. As a result, gas molecules will naturally move from an area of high concentration to an area of low concentration until equilibrium is reached. This process is essential for various biological and physical phenomena, such as the exchange of gases in the lungs during respiration and the mixing of substances in a solution.

During inhalation, the diaphragm contracts and moves downwards, while the intercostal muscles between the ribs contract and lift the ribcage. This increases the volume of the thoracic cavity, causing a decrease in air pressure within the lungs. As a result, air from the atmosphere flows into the lungs to equalize the pressure, making the air pressure in the lungs low.

During inhalation, the diaphragm contracts and flattens. The diaphragm is a dome-shaped muscle located at the base of the lungs. When it contracts, it moves downward and flattens, causing the volume of the chest cavity to increase. This creates a negative pressure inside the lungs, allowing air to be drawn in.

Haemoglobin is indeed a pigment. It is a protein found in red blood cells that gives blood its red color. It binds to oxygen in the lungs and carries it to the body's tissues. The iron present in haemoglobin is responsible for its pigment properties.

A stoma consists of a stoma opening and guard cells. The stoma opening is a small pore in the surface of a plant leaf that allows for gas exchange, including the intake of carbon dioxide and the release of oxygen. The guard cells surround the stoma opening and regulate its opening and closing. They control the size of the opening by changing shape, which helps to regulate the plant's water loss through transpiration and the uptake of carbon dioxide for photosynthesis.

The correct answer is 4/four because the heart is a muscular organ that pumps blood throughout the body. It is divided into four chambers: two atria and two ventricles. The atria receive blood from the body and lungs, while the ventricles pump blood out to the rest of the body. This four-chambered structure allows for efficient circulation of oxygenated and deoxygenated blood.

Smoke contains various harmful substances including carcinogens, tar, nicotine, and acidic gases. Carcinogens are substances that are known to cause cancer. Tar is a thick, sticky substance that can damage the lungs and contribute to respiratory problems. Nicotine is a highly addictive chemical found in tobacco smoke, which can lead to addiction and various health issues. Acidic gases in smoke can irritate the respiratory system and contribute to respiratory problems.

The correct answer is veins, arteries, and blood capillaries. These are the three main types of blood vessels in the human body. Veins carry deoxygenated blood back to the heart, while arteries carry oxygenated blood away from the heart. Blood capillaries are the smallest blood vessels and they connect arteries and veins, allowing for the exchange of oxygen, nutrients, and waste products between the blood and the surrounding tissues.