transport chapter 9 name

Chapter No.9 Transport

by

Class 9th Biology Chapter 9 Transport Notes

Long Answer Question

Short Answer Question

Exercise and MCQ’s

Transport in Plants: Water and Ion Uptake

  • Roots are responsible for absorbing water and minerals from the soil. They have root hairs that provide a large surface area for water and mineral absorption.
  • Water and minerals move from the root hairs to the xylem tissue through intercellular spaces or cells via channels called plasmodesmata.
  • The conducting tissues (xylem and phloem) in the root are grouped in the center to form a rod-shaped core, with the pericycle surrounding it.

Transpiration

  • Transpiration is the loss of water from the plant surface through evaporation. It occurs mainly through stomata in leaves and can also occur through the cuticle and lenticels.
  • Transpiration creates a pulling force called transpirational pull, which is responsible for the movement of water and salts from the roots to the aerial parts of the plant.
  • Stomata regulate transpiration, opening and closing to control water loss. Factors affecting the rate of transpiration include temperature, air humidity, air movement, and leaf surface area.

Significance of Transpiration

  • Transpiration has both positive and negative effects on plants. It can cause desiccation and wilting during drought conditions but is essential for nutrient transport and cooling of plant surfaces.
  • Transpiration also aids in the conduction of water and salts through the xylem tissues and allows for gaseous exchange in leaf cells.

Transport of Water and Food in Plants

Transport of Water

  • The cohesion-tension theory explains how water is raised to considerable heights in plants through the xylem.
  • The force responsible for water movement in the xylem is transpirational pull, which is created by transpiration in the leaves.
  • When a leaf transpires, its mesophyll cells lose water, causing water to move from the xylem into the mesophyll cells through osmosis.
  • As one water molecule moves up in the xylem, it creates a pulling force that extends all the way to the roots, pulling water and dissolved materials upwards.

Transport of Food in Plants

  • Phloem is responsible for transporting food substances throughout the plant body.
  • The pressure-flow mechanism explains the movement of food from sources (mature leaves or storage organs) to sinks (areas of active metabolism or storage).
  • At sources, sugars are moved into the sieve tubes of the phloem through active transport, creating higher pressure in these tubes.
  • At sinks, sugars are unloaded by active transport, and water exits the sieve tubes, reducing the pressure and causing a mass flow from sources to sinks.

Transport in Humans

  • The human blood circulatory system is a closed system consisting of blood, the heart, and blood vessels.
  • Blood is composed of plasma and blood cells. Plasma contains water, proteins, salts, metabolites, wastes, and respiratory gases.
  • Blood cells make up about 45% of blood volume, while plasma constitutes about 55%.
  • Plasma proteins include antibodies, fibrinogen (blood clotting protein), and albumin (maintains water balance in blood).
  • Transport in plants and animals is essential for the distribution of water, nutrients, and other vital substances, enabling various physiological processes and supporting growth and metabolism.

Blood Cells

  • Blood is composed of red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).
  • Red blood cells are the most numerous and lack a nucleus when mature. They contain hemoglobin, which transports oxygen and small amounts of carbon dioxide.
  • White blood cells are colorless and have two main types: granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (monocytes, B and T lymphocytes).
  • Platelets are not cells but fragments of bone marrow cells. They play a crucial role in blood clotting.

Blood Disorders

  1. Leukemia is a blood cancer characterized by the overproduction of immature and abnormal white blood cells.
  2. Thalassemia is a genetic disorder caused by mutations in the hemoglobin gene, leading to defective hemoglobin production and oxygen transport.

Blood Group Systems

  • The ABO blood group system is the most important in humans, consisting of four blood groups: A, B, AB, and O, based on the presence or absence of antigens (A and B) on red blood cells.
  • Blood transfusions must be cross-matched for compatibility to avoid agglutination and other adverse reactions.
  • The Rh blood group system classifies blood into Rh-positive and Rh-negative groups based on the presence or absence of Rh factors on red blood cells.

Human Heart

  • The heart is a muscular organ responsible for pumping blood through blood vessels by repeated contractions.
  • It is situated in the middle of the chest cavity (thorax) under the breastbone, between the lungs.
  • The heart is enclosed in a sac called the pericardium, which contains pericardial fluid to reduce friction during contractions.

Heart Chambers and Function

  1. The human heart consists of four chambers: two thin-walled atria (left and right) and two thick-walled ventricles (left and right).
  2. The left ventricle is the largest and strongest chamber as it pumps blood to all body parts.
  3. The heart works as a double pump, receiving deoxygenated blood from the body and pumping it to the lungs while receiving oxygenated blood from the lungs and pumping it to the body.

Circulation of Blood

  • The deoxygenated blood from the body is collected by the right atrium and passed to the right ventricle through the tricuspid valve.
  • The right ventricle then pumps the blood to the lungs through the pulmonary trunk and pulmonary semilunar valve.
  • The oxygenated blood from the lungs is collected by the left atrium and pumped to the left ventricle through the bicuspid valve. The left ventricle then pumps the blood to all parts of the body through the aorta and aortic semilunar valve.

Heartbeat and Heart Rate

  • The alternating relaxation and contraction of heart chambers make up the cardiac cycle, and one complete cardiac cycle is one heartbeat.
  • The heartbeat consists of diastole (filling of blood in atria), atrial systole (contraction of atria), and ventricular systole (contraction of ventricles).
  • The heart rate is the number of times the heart beats per minute and is commonly measured by feeling the pulse in areas where arteries are close to the skin, like the wrist.

Heart Sounds

  • The closing of valves during heart contractions produces sounds. The “lubb” sound is produced by the closing of the tricuspid and bicuspid valves, while the “dubb” sound is produced by the closing of the semilunar valves.
  • The heart is a vital organ that continuously pumps blood throughout the body, providing oxygen and nutrients to cells and tissues. Its proper functioning is crucial for overall health and well-being.

Blood Vessels

  • Blood vessels are an essential part of the blood circulatory system, responsible for transporting blood throughout the body.
  • The major types of blood vessels are arteries, veins, and capillaries.

Arteries

  • Arteries carry blood away from the heart, except for pulmonary arteries, which carry deoxygenated blood to the lungs.
  • The walls of arteries are composed of three layers: outer connective tissue, middle smooth muscles and elastic tissue, and inner endothelial cells.
  • Arteries divide into arterioles when entering body organs, and further divide into capillaries.

Capillaries

  • Capillaries are the smallest blood vessels present in tissues and are formed by divisions of arterioles.
  • They allow the exchange of materials between blood and tissue fluid, as their walls are composed of a single layer of endothelial cells.
  • Capillaries are so small that red blood cells need to partially fold to pass through them in single file.

Veins

  • Veins carry blood towards the heart, except for pulmonary veins, which carry oxygenated blood from the lungs.
  • Vein walls have the same three layers as arteries, but the middle layer has fewer smooth muscles and elastic tissue.
  • Veins have a broader lumen compared to arteries and often have valves to prevent the backflow of blood.

Blood Circulatory System

  • The arterial system consists of the pulmonary trunk, aorta, and various branches that supply blood to different body parts.
  • The venous system includes the pulmonary veins, superior vena cava, inferior vena cava, and various other veins from different parts of the body.

Cardiovascular Disorders

  • Cardiovascular disorders are diseases related to the heart or blood vessels.
  • Atherosclerosis is the accumulation of fatty materials, cholesterol, or fibrin in arteries, leading to the formation of plaques and narrowing of arteries.
  • Arteriosclerosis is a general term for any hardening of arteries due to calcium deposits.
  • Myocardial infarction, commonly known as a heart attack, occurs when blood supply to a part of the heart is interrupted, leading to heart muscle death.

Prevention and Awareness

  • Risk factors for cardiovascular disorders include advanced age, diabetes, high cholesterol, smoking, high blood pressure, obesity, and a sedentary lifestyle.
  • Awareness campaigns like World Heart Day aim to educate people about cardiovascular risks and prevention methods.

Statistics (for Pakistan)

  • Cardiovascular disorders account for 12% of adult deaths in Pakistan.
  • There are over 12 million hypertension patients and about 10% of the population is diabetic in Pakistan.
  • Approximately 1 in 7 urban adults in Pakistan is obese according to the World Health Organization.

Leave a Comment