Ch.7 Transportation in Animals and Plants PDF

# Transportation of Materials ## All Organisms Need Materials - All organisms need oxygen, food, and water to stay alive. - Digested food, oxygen, and water need to reach every cell of the body. - Waste products need to be transported from where they can be removed. - Organisms have a system to t...

# Transportation of Materials ## All Organisms Need Materials - All organisms need oxygen, food, and water to stay alive. - Digested food, oxygen, and water need to reach every cell of the body. - Waste products need to be transported from where they can be removed. - Organisms have a system to transport substances within them. ## Transportation of Materials in Unicellular Organisms - Unicellular organisms, like Amoeba and Paramecium, do not require a separate system to transport substances. - The single cell is in direct contact with the environment. - Oxygen, nutrients, and waste materials move in and out of the cell by diffusion. - Diffusion is the net movement of molecules or atoms from the region of higher concentration to the region of lower concentration. - In unicellular organisms, all materials within the cells are circulated by the streaming movement of the cytoplasm. ## Transportation of Materials in Simple Multicellular Organisms - Simple multicellular organisms, like Hydra and sponges, transport nutrients and oxygen by water that enters their bodies. - Waste materials are removed along with the water that moves out. ## Transportation of Materials in Human Beings - Higher animals, including humans, have a well-developed transportation system known as the circulatory system. - The circulatory system consists of blood, blood vessels, and the heart. ### Blood - Blood is the fluid that flows in blood vessels. - An average human being has about 4–6 liters of blood circulating in the body. - Blood consists of the following components: - *Red Blood Corpuscles (RBCs) or erythrocytes*: Specialized blood cells that are red in color as they contain a red pigment called hemoglobin. Hemoglobin helps transport oxygen to different parts of the body. - *White Blood Corpuscles (WBCs) or leucocytes*: Specialized blood cells that protect our body against germs, thus, they are also called “Soldiers of the body.” They are larger that RBCs and are devoid of hemoglobin. - *Platelets or thrombocytes*: Cellular fragments of bone marrow cells that help in clotting blood at the site of an injury. - *Plasma*: The straw-colored fluid part of the blood that transports nutrients as well as metabolic waste products ### Blood Vessels - Blood flows through our body in a complex network of tubes called blood vessels. - There are three types of blood vessels: arteries, veins, and capillaries. - *Arteries*: Have thick elastic walls and are located deep under the skin. The walls of arteries are thick and elastic to withstand the flow of blood from the heart at high pressure. Arteries carry blood from the heart to various parts of the body. Arteries generally carry oxygenated (oxygen-rich) blood except for the pulmonary artery, that carries deoxygenated blood. - *Capillaries*: Arteries divide into a network of extremely thin blood vessels called capillaries to penetrate various tissues of the body. The thin walls of the capillaries facilitate easy exchange of nutrients, gases, and waste products between the blood and the surrounding cells, by the process of diffusion. The capillaries join to form veins. - *Veins*: Have thin walls. They have valves that prevent backflow of blood, thus allowing it to flow only towards the heart. Veins are situated just under the skin. These can be easily seen as greenish-blue tubes on the hands and legs. Veins carry deoxygenated (oxygen-deficient) blood from all parts of the body to the heart except for the pulmonary vein, that carries oxygenated blood. | Difference | Arteries | Veins | |:---|:---|:---| | Wall thickness | Thick and elastic | Thin | | Direction of blood flow | Away from the heart | Towards the heart | | Blood pressure | High | Low | | Valves | None | Present | | Location | Deep under the skin | Superficially placed just under the skin | | Blood type | Generally oxygenated; pulmonary artery carries deoxygenated blood from the heart to the lungs | Generally deoxygenated; pulmonary veins carry oxygenated blood from the lungs to the heart | ### Heart - The heart is a fist-sized muscular organ. - It is centrally placed in the chest. - It is slightly tilted towards the left (Fig. 7.6). - The human heart consists of four chambers: - The upper chambers are called the *atria* (Singular: atrium) - The lower chambers are called the *ventricles*. - The right atrium opens into the right ventricle. - The left atrium opens into the left ventricle. - The right side of the heart is completely separated from the left side by a muscular partition called *septum* to ensure that deoxygenated blood does not mix with oxygenated blood. ### Blood Circulation in the Body - Deoxygenated blood from different parts of the body enters the *right atrium* through the superior vena cava and the inferior vena cava. - It is then pumped into the *right ventricle*. - From here, the blood is pumped through the *pulmonary artery* to the lungs for reoxygenation. - In the lungs, this blood gives up carbon dioxide into the alveoli and absorbs oxygen. - This oxygenated blood returns to the *left atrium* through the *pulmonary veins*. - It then enters the *left ventricle*. - From here, the blood is pumped through the *aorta* to different parts of the body. - As the blood passes through the capillaries, oxygen and other nutrients are delivered to the cells, and carbon dioxide and other wastes are picked up by the blood. - This deoxygenated blood again goes back to the *right atrium*, and this cycle is repeated continuously throughout the life of a person (Fig. 7.7). ### Heartbeat - All the muscles of the heart do not contract at the same time. - The two *atria* contract first, pumping blood into the ventricles. - A fraction of a second later, the two *ventricles* contract. - A healthy heart makes a lub-dub sound with each beat. - This sound comes from the closing of the valves in the heart when contractions occur. - This periodic contraction and relaxation of the heart muscles is known as the *heartbeat*. - The heart beats continuously. - You can feel the heartbeat if you place your ear against your friend's chest. - The heart beats on an average of 72 times a minute. ## Excretion - Several chemical reactions take place in each cell of an organism. - These chemical reactions, collectively called *metabolism*, convert the food we eat into energy. - These metabolic reactions also produce waste materials, such as water, carbon dioxide, urea, and uric acid. - If these waste materials are allowed to accumulate in the body, they can be harmful, and thus, need to be removed from the body at regular intervals. - The process of removal of metabolic wastes produced by the cells of a living organism is called *excretion*. ## Excretion in Animals - In lower organism, like Amoeba, Paramecium, and Hydra, there are no specialized excretory organs. - Waste products, such as ammonia, are removed from the cells by the process of diffusion. - Animals living in water excrete their metabolic waste in the form of ammonia, as removal of ammonia requires a large amount of water. - These animals are called *ammonotelic animals*. - Some land animals, such as birds, lizards, and snakes excrete a semi-solid white compound called uric acid. - These animals are called *uricotelic animals*. - Land animals, including human beings, excrete metabolic waste as urea. - They are known as *ureotelic animals*. - Higher animals have well-developed excretory organs. ## Excretion in Human Beings - The excretory system in human beings consists of kidneys, ureters, urinary bladder, and urethra. ### Kidneys - In the human body, a pair of kidneys are located in the abdomen, one each on either side of the vertebral column. - Each kidney is brick red in color and bean-shaped. - Kidneys filter waste from the blood and eliminate harmful substances in the form of urine. - They also maintain the water and mineral balance in the body. ### Ureters - The ureters are thin-walled, urine-carrying ducts. - A single ureter originates from each kidney and is about 25 to 30 cm in length. - The ureters run downward and open into the urinary bladder. ### Urinary Bladder - It is a bag-like structure that stores urine. - Its size and position vary with the amount of urine it contains. ### Urethra - The urethra is the duct that finally discharges urine from the body ### Mechanisms Of Excretion - Each kidney has about a million tiny filters called *nephrons*. - Nephrons filter excess water, nitrous waste, such as urea, and salt, from the blood. - The filtered blood is carried towards the heart from the kidneys. - The filtered waste, on the other hand, flows out of the kidneys through the ureters and is collected in the bladder in the form of urine. - Urine is a pale yellow-colored liquid. - A human being excretes an average of 1.5 to 2.5 liters of urine per day. ### Sweat Formation - Basically, sweating helps regulate our body temperature. - Sweat glands (Fig. 7.13), present in the skin also excrete some amount of metabolic waste along with salts and water. ### Renal Failure or Kidney Failure - Sometimes a person's kidneys may stop working. - An infection in the kidneys, an injury, or restricted flow of blood to the kidneys can cause damage. - Complete failure of the kidneys result in the accumulation of urea and other waste products in the blood. - Even the quantity of water is not regulated in the body. - If left untreated, these symptoms may even lead to the death of the patient. ### Dialysis - An individual with failed kidneys can get their blood filtered or cleaned artificially. - The process used for cleaning the blood of a person with kidney failure by separating waste substances (urea) from it is called *dialysis*, and the device is called a *dialysis machine* or a *dialyser*. - The best long-term solution for kidney failure is kidney transplantation in which the damaged kidney if replaced with a healthy kidney. ## Transportation Of Materials in Plants - Plants are living organisms like animals. - They need water, minerals, and food for their survival. - The transport of materials in plants is carried out by two types of conducting tissues called *xylem* and *phloem*, which together constitute the *vascular tissue system*. - You already know that *xylem* (Fig. 7.14 [a]) transports water and minerals upwards from the roots to the leaves. - The movement of water and minerals in the *xylem* is unidirectional. - *Phloem* (Fig. 7.14 [b]) carries the food prepared by the leaves to all parts of the plant, including roots. - The movement of materials in the *phloem* is bidirectional. - Thus, *xylem* and *phloem* transport various substances in plants. ### Transport of Water, Minerals, and Food - Plants absorb water and minerals through the roots as shown in figure 7.15. - The roots have root hairs that are in direct conduct with the water molecules present between the soil particles. - Root hairs also increase the surface area for the absorption of water and minerals present in the soil. - The fluid containing water and dissolved minerals in the cells of the root hairs is called *sap*. - The upward movement of fluid through the *xylem* is called the *ascent of sap*. ### Activity 3 - To understand that xylem conducts sap in a plant, students can perform an observation to compare plants watered with water, minerals, and plant food with plants watered only with water. ### Water Movement - Water moves from root hair to the *xylem* in the root. - From the *xylem*, it travels into the leaves. - Then, it moves from the roots to the leaves. - The movement of water into the roots and up the stem is by *osmosis*. - *Osmosis* is the process by which molecules of a solvent move from a solution of low solute concentration to a solution of high solute concentration through a semipermeable membrane. ### Activity 5 - Students can perform an activity using dialysis tubing to demonstrate how semipermeable membranes allow the passage of water from a higher concentration to a lower concentration. ### Translocation - The food prepared in the *leaves* is transported from the leaves to other parts of the plant through *phloem*. - This process is called *translocation*. - Figure 7.19 shows a schematic representation of ascent of sap and translocation of food in a plant. - The blue arrows indicate the movement of water and minerals from the root to the leaves. - The orange arrows indicate translocation of food from the leaves to all parts of the plant body. ## Excretion in Plants - Plants have no special excretory organs. - Plants produce two gaseous waste products: - Oxygen (produced during photosynthesis) - Carbon dioxide (produced during respiration) - Excretion of gaseous waste in plants takes place through the stomatal pores on leaves. - Excess water is also excreted from the plants body through the stomatal pores by a process called *transpiration*. ### Other Forms of Stored Waste Products in Plants - Oil produced by orange and eucalyptus plants - Latex produced by rubber (latex is an example of a stored waste product)