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Give Reasons: (a) Ventricles Have Thicker Muscular Walls Than Atria. (b) Transport System in Plants Is Slow. (c) Circulation of Blood in Aquatic Vertebrates Differs from That in Terrestrial Vertebrates. (d) During The Daytime, Water and Minerals Travel Faster Through the Xylem as Compared to The Night. (e) Veins Have Valves Whereas Arteries Do Not.
(a) Ventricles Have Thicker Muscular Walls Than Atria
The heart is one of the most vital organs in the human body, responsible for pumping blood throughout the circulatory system. It is composed of four chambers, two atria, and two ventricles. The atria are the upper chambers, while the ventricles are the lower chambers of the heart. These chambers have distinct structures and functions, and the thickness of their walls plays a critical role in the heart's overall function.
The ventricles have thicker muscular walls than the atria. This is because the ventricles have to pump blood to different parts of the body, while the atria only have to pump blood to the ventricles. The thicker muscular walls of the ventricles allow them to generate more force when contracting and pump blood with greater pressure than the atria.
The left ventricle, in particular, has the thickest walls of any chamber in the heart. This is because it is responsible for pumping oxygen-rich blood to the rest of the body, including the brain and vital organs. The thicker walls of the left ventricle enable it to generate more force and pump blood to the entire body more efficiently.
The thickness of the ventricular walls also helps to maintain the integrity of the heart's structure. The ventricles are the chambers of the heart that experience the most stress during contraction, and their thick walls help to withstand this stress and prevent the heart from collapsing.
(b) Transport System in Plants Is Slow
Plants have a transport system that is different from the circulatory system in animals. In plants, the transport system consists of xylem and phloem, which are specialized tissues that transport water, nutrients, and other substances throughout the plant.
The xylem is responsible for transporting water and dissolved minerals from the roots to the rest of the plant. It is made up of elongated cells called tracheid’s and vessel elements, which are arranged end to end to form a continuous tube
The phloem, on the other hand, transports organic compounds, such as sugars and amino acids, from the leaves to the rest of the plant. It is made up of sieve tubes and companion cells, which work together to form a continuous tube that transports substances in both directions.
The transport system in plants is slow for several reasons. Firstly, the movement of water and nutrients through the xylem and phloem is passive and relies on pressure gradients and concentration gradients. This means that it can take some time for substances to be transported to different parts of the plant.
Secondly, the xylem and phloem are relatively narrow compared to the blood vessels in animals. This means that the rate of flow is slower, and substances take longer to travel through the plant.
Finally, the transport system in plants is also affected by environmental factors, such as temperature and humidity. For example, in cold weather, the rate of transpiration is slower, which can slow down the movement of water and nutrients through the plant.
(c) Circulation of Blood in Aquatic Vertebrates Differs from That in Terrestrial Vertebrates
The circulation of blood in aquatic vertebrates, such as fish, is different from that in terrestrial vertebrates, such as mammals. This is because aquatic vertebrates have to adapt to the different physical properties of water, such as its density and viscosity, which affect the flow of blood.
In fish, the circulatory system is a single loop, where blood is pumped from the heart to the gills, where it is oxygenated, and then flows to the rest of the body before returning to the heart. The heart of a fish consists of two chambers, one atrium, and one ventricle. The atrium receives deoxygenated blood from the body, and the ventricle pumps it to the gills for oxygenation. From the gills, oxygenated blood flows to the rest of the body before returning to the atrium.
One of the key differences between the circulation of blood in aquatic and terrestrial vertebrates is the amount of pressure required to circulate blood. In water, the pressure required is much lower than on land due to the higher density of water. Fish do not need to generate as much pressure to circulate blood as terrestrial vertebrates. Their circulatory system is also adapted to deal with the different viscosity of water compared to air. Blood flow in fish is slower than in terrestrial vertebrates, which allows for more efficient oxygenation of the blood.
Another significant difference is that fish do not have lungs, so they rely on their gills for oxygen exchange. The gills are highly specialized structures that contain thin-walled blood vessels that allow for the exchange of gases between the water and blood. Oxygen from the water diffuses into the blood vessels in the gills, and carbon dioxide from the blood diffuses into the water.
In contrast, terrestrial vertebrates have lungs, which are responsible for gas exchange. The lungs are highly vascularized organs that contain millions of tiny air sacs called alveoli. Oxygen from the air diffuses into the blood vessels in the lungs, and carbon dioxide from the blood diffuses into the air.
(d) During The Daytime, Water and Minerals Travel Faster Through the Xylem as Compared to The Night
Plants rely on the transport of water and minerals through the xylem to maintain their structure and carry out vital functions such as photosynthesis. The rate of water and mineral transport through the xylem can vary depending on environmental factors, such as temperature and light.
During the daytime, the rate of water and mineral transport through the xylem is faster than at night. This is because during the day, plants undergo photosynthesis, which results in the production of sugars and other organic compounds. These compounds create a concentration gradient that drives the movement of water and minerals through the xylem.
At night, when there is no photosynthesis taking place, the concentration gradient driving water and mineral transport through the xylem is weaker. In addition, the stomata on the leaves are closed, which reduces the rate of transpiration and the flow of water through the xylem.
(e) Veins Have Valves Whereas Arteries Do Not
Valves in veins are flap-like structures that help to prevent the backflow of blood. As blood flows through the veins back towards the heart, the valves close to prevent the blood from flowing backward. This is especially important in the veins of the lower limbs, where the blood must flow against gravity to return to the heart. Without valves, blood would pool in the legs, leading to swelling, discomfort, and potentially more serious conditions such as varicose veins.
In contrast, arteries do not require valves because the flow of blood is driven by the pumping action of the heart. The pressure generated by the heart's contractions pushes the blood through the arteries, and the arteries are designed to withstand this pressure without collapsing or leaking. Arteries have thicker walls and more elastic tissue than veins, which helps them to maintain their shape and carry blood under high pressure.
In conclusion, the thickness of muscular walls in ventricles compared to atria reflects the different functions they perform in the circulatory system. The slower transport system in plants is necessary to maintain efficient water and mineral uptake, while the differences in blood circulation in aquatic and terrestrial vertebrates reflect their adaptations to different environments.
The rate of water and mineral transport through the xylem is closely linked to the physiological processes of the plant and the environmental conditions in which it grows, while the presence of valves in veins helps to prevent the backflow of blood and maintain efficient circulation in the body.
Understanding these differences in the anatomy and physiology of living organisms can deepen our appreciation for the complexity of life and the ways in which organisms are adapted to their environments.
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