Cell Structure and Organelles
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Questions and Answers

What is the primary function of the mitochondria in a cell?

  • Protein synthesis
  • Waste recycling and digestion
  • Energy generation through cellular respiration (correct)
  • Storage of genetic material

    • Which organelle is responsible for protein synthesis?

  • Ribosomes (correct)
  • Endoplasmic reticulum
  • Mitochondria
  • Nucleus

    • What is the term for the process of generating energy for the cell through the breakdown of glucose?

  • Cellular respiration (correct)
  • Assimilation
  • Cell signaling
  • Photosynthesis

    • Which nutrient provides energy and insulation for the body?

    <p>Fats</p> Signup and view all the answers

    What is the process of taking in food through the mouth?

    <p>Ingestion</p> Signup and view all the answers

    What is the term for the process of communication between cells through signaling molecules?

    <p>Cell signaling</p> Signup and view all the answers

    Which organelle contains digestive enzymes that break down and recycle cellular waste and foreign substances?

    <p>Lysosomes</p> Signup and view all the answers

    What is the term for the process of using absorbed nutrients for energy, growth, and repair?

    <p>Assimilation</p> Signup and view all the answers

    Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

    <p>Diffusion is insufficient because not all cells in multicellular organisms are in direct contact with the surrounding environment, so a transportation system is needed for oxygen to reach all cells efficiently.</p> Signup and view all the answers

    What criteria do we use to decide whether something is alive?

    <p>Visible movements like breathing or growth, such as plants growing, are commonly used as criteria to determine if something is alive.</p> Signup and view all the answers

    What are outside raw materials used for by an organism?

    <p>Outside raw materials are used as a source of energy and nutrients by organisms to maintain life processes and support growth.</p> Signup and view all the answers

    What processes would you consider essential for maintaining life?

    <p>Essential processes for maintaining life include nutrition (food intake), respiration, transportation of nutrients, removal of waste products (excretion), and maintenance of cellular structures.</p> Signup and view all the answers

    What is the purpose of immersing the leaf in a dilute solution of iodine after rinsing off the alcohol solution?

    <p>To perform a starch test</p> Signup and view all the answers

    What is the colour of the leaf after being dipped in a beaker containing alcohol and heated until the alcohol begins to boil?

    <p>The leaf changes colour</p> Signup and view all the answers

    Do both leaves from the two healthy potted plants show the same amount of starch after being exposed to sunlight?

    <p>No</p> Signup and view all the answers

    What does the presence of nitrogen in the soil provide for plants?

    <p>Essential element for the synthesis of proteins and other compounds</p> Signup and view all the answers

    What is the main function of the alimentary canal in human beings?

    <p>To digest food and absorb nutrients</p> Signup and view all the answers

    Which enzyme in saliva is responsible for breaking down starch?

    <p>Amylase</p> Signup and view all the answers

    What is the respiratory pigment present in human beings?

    <p>haemoglobin</p> Signup and view all the answers

    What advantage does a terrestrial organism have over an aquatic organism in obtaining oxygen for respiration?

    <p>The alveoli provide a large surface area for efficient gas exchange</p> Signup and view all the answers

    How is oxygen and carbon dioxide transported in human beings?

    <p>Oxygen is carried by red blood cells while carbon dioxide is mostly transported in dissolved form in the blood</p> Signup and view all the answers

    How are the lungs designed in human beings to maximize the area for exchange of gases?

    <p>The lungs have alveoli which provide a large surface area for gas exchange</p> Signup and view all the answers

    What are the differences between autotrophic nutrition and heterotrophic nutrition?

    <p>Autotrophic nutrition involves organisms making their own food using sunlight or inorganic substances, while heterotrophic nutrition involves organisms relying on consuming other organisms to obtain nutrients.</p> Signup and view all the answers

    Where do plants get each of the raw materials required for photosynthesis?

    <p>Plants obtain carbon dioxide from the air, water from the soil, and sunlight as energy.</p> Signup and view all the answers

    What is the role of the acid in our stomach?

    <p>The acid in our stomach helps in the breakdown of food and kills bacteria that enter the digestive system.</p> Signup and view all the answers

    What is the function of digestive enzymes?

    <p>Digestive enzymes help in breaking down food into smaller molecules that can be absorbed by the body.</p> Signup and view all the answers

    How is the small intestine designed to absorb digested food?

    <p>The small intestine is lined with villi, which are finger-like projections that increase the surface area for absorption. Villi are rich in blood vessels that carry absorbed nutrients to the cells.</p> Signup and view all the answers

    What change is observed in the lime water when yeast is added to a sugar solution?

    <p>The lime water turns milky due to the production of carbon dioxide by yeast.</p> Signup and view all the answers

    Why is the surface area of the alveoli in the lungs important for respiration?

    <p>The large surface area of the alveoli allows for efficient exchange of oxygen and carbon dioxide between the lungs and the bloodstream.</p> Signup and view all the answers

    What are the components of the transport system in human beings?

    <p>The components of the transport system in human beings include the heart, blood vessels (arteries, veins, capillaries), and blood.</p> Signup and view all the answers

    What are the functions of the components of the human transport system?

    <p>The heart pumps and circulates blood, arteries carry oxygen-rich blood away from the heart, veins return oxygen-poor blood back to the heart, capillaries facilitate exchange of materials between blood and tissues.</p> Signup and view all the answers

    Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

    <p>Separating oxygenated and deoxygenated blood ensures efficient delivery of oxygen to tissues and removal of carbon dioxide.</p> Signup and view all the answers

    What are the components of the transport system in highly organised plants?

    <p>The components include xylem for transporting water and minerals, phloem for transporting food and other substances.</p> Signup and view all the answers

    How are water and minerals transported in plants?

    <p>Water and minerals are transported in plants through the xylem tissue, which forms a continuous system of water-conducting channels.</p> Signup and view all the answers

    How is food transported in plants?

    <p>Food is transported in plants through the phloem tissue, which moves the products of photosynthesis from leaves to other parts of the plant.</p> Signup and view all the answers

    Describe the structure and functioning of nephrons.

    <p>Nephrons are the functional units of the kidneys responsible for filtering blood and producing urine. Each nephron consists of a glomerulus, Bowman's capsule, renal tubules, and collecting duct. The glomerulus filters blood, and the filtrate passes into Bowman's capsule. The renal tubules further process the filtrate by reabsorbing necessary substances and secreting waste products, resulting in the formation of urine.</p> Signup and view all the answers

    What are the methods used by plants to get rid of excretory products?

    <p>Plants utilize different strategies for excretion compared to animals. They eliminate waste products through transpiration, shedding of leaves, storage in vacuoles, formation of resins and gums, as well as excretion into the surrounding soil.</p> Signup and view all the answers

    How is the amount of urine produced regulated?

    <p>The volume of urine produced is regulated by the body's need to maintain a balance of fluids, electrolytes, and waste products. Factors like hydration levels, hormonal influence, blood pressure, and kidney function play a role in regulating urine production.</p> Signup and view all the answers

    The kidneys in human beings are a part of the system for

    <p>excretion</p> Signup and view all the answers

    The xylem in plants are responsible for

    <p>transport of water</p> Signup and view all the answers

    The autotrophic mode of nutrition requires

    <p>all of the above</p> Signup and view all the answers

    How are fats digested in our bodies? Where does this process take place?

    <p>Fats are digested in the small intestine with the help of bile and pancreatic enzymes. Bile emulsifies fats, enzymes break them down into fatty acids and glycerol, and absorption of these components occurs in the small intestine.</p> Signup and view all the answers

    Study Notes

    Cell Biology

    Cell Structure

    • Plasma membrane: semi-permeable membrane that surrounds the cell
    • Cytoplasm: jelly-like substance inside the cell where metabolic reactions occur
    • Nucleus: contains most of the cell's genetic material (DNA)
    • Mitochondria: generates energy for the cell through cellular respiration
    • Endoplasmic reticulum (ER): network of membranous tubules and cisternae involved in protein synthesis and transport
    • Ribosomes: site of protein synthesis
    • Lysosomes: contain digestive enzymes that break down and recycle cellular waste and foreign substances

    Cell Function

    • Cellular respiration: process of generating energy for the cell through the breakdown of glucose
    • Photosynthesis: process of generating energy for the cell through the conversion of light energy
    • Cell signaling: process of communication between cells through signaling molecules
    • Cell division: process of cell growth and reproduction, including mitosis and meiosis

    Nutrition

    Nutrients

    • Carbohydrates: provide energy for the body, examples include sugars, starches, and fibers
    • Proteins: build and repair tissues, examples include amino acids
    • Fats: provide energy and insulation, examples include triglycerides and phospholipids
    • Vitamins: essential nutrients that cannot be synthesized by the body, examples include vitamin C and vitamin D
    • Minerals: essential nutrients that cannot be synthesized by the body, examples include calcium and iron

    Nutritional Processes

    • Ingestion: process of taking in food through the mouth
    • Digestion: process of breaking down food into smaller molecules that can be absorbed by the body
    • Absorption: process of taking in nutrients through the walls of the digestive tract
    • Assimilation: process of using absorbed nutrients for energy, growth, and repair
    • Elimination: process of removing waste products from the body

    Cell Biology

    Cell Structure

    • The plasma membrane is a semi-permeable membrane that surrounds the cell, regulating what enters and leaves.
    • Cytoplasm is a jelly-like substance inside the cell where metabolic reactions occur, maintaining cellular shape and providing mechanical support.
    • The nucleus contains most of the cell's genetic material (DNA), which is organized into linear chromosomes.
    • Mitochondria are the site of cellular respiration, generating energy for the cell through the breakdown of glucose and other organic molecules.
    • The endoplasmic reticulum (ER) is a network of membranous tubules and cisternae involved in protein synthesis, transport, and lipid synthesis.
    • Ribosomes are the site of protein synthesis, reading messenger RNA (mRNA) to assemble amino acids into polypeptide chains.
    • Lysosomes contain digestive enzymes that break down and recycle cellular waste and foreign substances, maintaining cellular homeostasis.

    Cell Function

    • Cellular respiration is the process of generating energy for the cell through the breakdown of glucose, involving glycolysis, pyruvate oxidation, and the electron transport chain.
    • Photosynthesis is the process of generating energy for the cell through the conversion of light energy, involving the absorption of light by pigments and the production of ATP and NADPH.
    • Cell signaling is the process of communication between cells through signaling molecules, such as hormones and neurotransmitters, which bind to receptors to initiate responses.
    • Cell division involves the reproduction of cells through mitosis (for somatic cells) and meiosis (for gametes), ensuring genetic continuity and diversity.

    Nutrition

    Nutrients

    • Carbohydrates are energy-rich molecules that provide fuel for the body, with examples including sugars (e.g., glucose), starches (e.g., amylose), and fibers (e.g., cellulose).
    • Proteins are complex biomolecules that build and repair tissues, composed of amino acids linked by peptide bonds.
    • Fats are energy-dense molecules that provide insulation and energy, with examples including triglycerides (e.g., triolein) and phospholipids (e.g., lecithin).
    • Vitamins are essential nutrients that cannot be synthesized by the body, with examples including vitamin C (ascorbic acid) and vitamin D (cholecalciferol).
    • Minerals are essential nutrients that cannot be synthesized by the body, with examples including calcium (Ca) and iron (Fe), which are crucial for bone health and oxygen transport.

    Nutritional Processes

    • Ingestion involves the mechanical breakdown of food through chewing and the chemical breakdown of food through saliva and gastric juices.
    • Digestion involves the enzymatic breakdown of macromolecules into smaller molecules, such as amino acids, sugars, and fatty acids.
    • Absorption involves the uptake of nutrients through the walls of the digestive tract into the bloodstream, where they can be distributed to cells.
    • Assimilation involves the use of absorbed nutrients for energy, growth, and repair, with excess energy stored as glycogen or fat.
    • Elimination involves the removal of waste products, such as urea, carbon dioxide, and feces, through excretory organs like the kidneys and liver.

    Life Processes

    • Life processes are the maintenance functions of living organisms that need to go on even when they are not doing anything particular.
    • These processes are needed to prevent damage and break-down, and energy is needed for them, which comes from outside the body of the individual organism.

    What are Life Processes?

    • Life processes include:
      • Nutrition: the process of obtaining energy and materials from outside the body.
      • Respiration: the process of using oxygen to break-down food sources for cellular needs.
      • Transportation: the process of carrying food and oxygen from one place to another in the body.
      • Excretion: the process of removing waste by-products from the body.

    Nutrition

    • Nutrition is the process of obtaining energy and materials from outside the body.
    • Autotrophic nutrition: the process by which autotrophs (e.g. green plants and some bacteria) convert carbon dioxide and water into stored forms of energy using sunlight and chlorophyll.
    • Heterotrophic nutrition: the process by which heterotrophs (e.g. animals and fungi) obtain energy and materials from other organisms.

    Autotrophic Nutrition

    • Autotrophic nutrition involves photosynthesis, which is the process by which autotrophs convert carbon dioxide and water into stored forms of energy using sunlight and chlorophyll.
    • Photosynthesis involves:
      • Absorption of light energy by chlorophyll.
      • Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
      • Reduction of carbon dioxide to carbohydrates.

    Heterotrophic Nutrition

    • Heterotrophic nutrition involves obtaining energy and materials from other organisms.
    • Examples of heterotrophic nutrition include:
      • Fungi breaking down food material outside the body and absorbing it.
      • Animals taking in whole material and breaking it down inside their bodies.
      • Parasites deriving nutrition from plants or animals without killing them.

    How do Organisms obtain their Nutrition?

    • Different organisms have specialized digestive systems depending on their body design and functioning.
    • In single-celled organisms, the food is taken in by the entire surface.
    • In complex organisms, different parts become specialized to perform different functions.

    Nutrition in Human Beings

    • The alimentary canal is a long tube extending from the mouth to the anus.
    • The alimentary canal has different parts that are specialized to perform different functions.
    • Digestion of food occurs in the alimentary canal, with the help of enzymes such as salivary amylase.

    Importance of Chlorophyll and Light Energy in Photosynthesis

    • Chlorophyll is essential for photosynthesis, as it absorbs light energy and converts it to chemical energy.
    • Light energy is necessary for photosynthesis, and chlorophyll is the key component that makes this process possible.### Digestion and Absorption of Food
    • The alimentary canal is a long tube that extends from the mouth to the anus.
    • The lining of the canal is soft and wet to facilitate the passage of food.
    • Saliva secreted by the salivary glands contains an enzyme called salivary amylase that breaks down starch into sugar.
    • The food is mixed thoroughly with saliva and moved around the mouth while chewing by the muscular tongue.
    • The lining of the canal has muscles that contract rhythmically to push the food forward through peristaltic movements.
    • The stomach is a large organ that expands when food enters it, and the muscular walls of the stomach mix the food thoroughly with more digestive juices.
    • The digestive juices in the stomach are produced by gastric glands and contain hydrochloric acid and pepsin.
    • The hydrochloric acid creates an acidic medium that facilitates the action of the enzyme pepsin.
    • The mucus protects the inner lining of the stomach from the action of the acid.

    Small Intestine

    • The small intestine is the longest part of the alimentary canal and is fitted into a compact space due to extensive coiling.
    • The length of the small intestine differs in various animals depending on the food they eat.
    • Herbivores have a longer small intestine to allow cellulose to be digested, while carnivores have a shorter small intestine since meat is easier to digest.
    • The small intestine is the site of the complete digestion of carbohydrates, proteins, and fats.
    • The small intestine receives secretions from the liver and pancreas for digestion.
    • Bile juice from the liver makes the food alkaline, allowing pancreatic enzymes to act.
    • Pancreatic juice contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.

    Absorption of Digested Food

    • The walls of the small intestine contain glands that secrete intestinal juice.
    • Enzymes in the intestinal juice finally convert proteins to amino acids, complex carbohydrates into glucose, and fats into fatty acids and glycerol.
    • The digested food is taken up by the walls of the intestine.
    • The inner lining of the small intestine has numerous finger-like projections called villi that increase the surface area for absorption.
    • The villi are richly supplied with blood vessels that take the absorbed food to each and every cell of the body.

    Respiratory System

    • The energy released during cellular respiration is used to synthesise ATP, which is used to fuel all other activities in the cell.
    • ATP is the energy currency for most cellular processes.
    • The energy released during respiration is used to make an ATP molecule from ADP and inorganic phosphate.
    • Endothermic processes in the cell use this ATP to drive the reactions.

    Transportation in Human Beings

    • Blood is a fluid connective tissue that transports food, oxygen, and waste materials in our bodies.

    • Plasma transports food, carbon dioxide, and nitrogenous wastes in dissolved form.

    • Oxygen is carried by the red blood cells.

    • Many other substances like salts are also transported by the blood.### The Heart and Blood Vessels

    • The heart is a muscular organ that pumps blood throughout the body.

    • It has four chambers: the left and right atria, and the left and right ventricles.

    • The left and right sides of the heart are separated to prevent oxygenated and deoxygenated blood from mixing.

    • The heart pumps oxygen-rich blood from the lungs to the body and deoxygenated blood from the body to the lungs.

    Blood Pressure

    • Blood pressure is the force of blood against the walls of blood vessels.
    • It is measured in mm of Hg (millimeters of mercury).
    • Normal blood pressure is around 120/80 mm Hg.
    • High blood pressure (hypertension) can lead to the rupture of an artery and internal bleeding.

    Blood Vessels

    • Arteries carry blood away from the heart to organs and tissues.
    • They have thick, elastic walls to withstand high blood pressure.
    • Veins collect blood from organs and tissues and bring it back to the heart.
    • They have valves to prevent blood from flowing backward.
    • Capillaries are the smallest blood vessels, where oxygen and nutrients are exchanged with cells.

    Platelets and Blood Clotting

    • Platelets are blood cells that help to plug leaks in blood vessels and form blood clots.
    • They circulate in the blood and respond to injuries by aggregating and forming a platelet plug.
    • Blood clotting is a crucial process that prevents excessive blood loss in case of injury.

    Lymphatic System

    • The lymphatic system is a network of vessels, organs, and tissues that help to defend the body against infection and disease.
    • It absorbs and transports fats and fat-soluble vitamins from the digestive system.
    • Lymphatic vessels drain excess fluid from tissues and return it to the bloodstream.

    Transportation in Plants

    • Plants have a transportation system that moves water, minerals, and nutrients from the roots to the leaves and other parts of the plant.
    • The xylem transports water and minerals from the roots to the leaves, while the phloem transports sugars and other organic compounds from the leaves to other parts of the plant.
    • The process of transpiration creates a suction force that pulls water up the xylem.
    • Xylem and phloem tissues are organized into vascular bundles that run throughout the plant.

    Excretion in Human Beings

    • The excretory system in human beings consists of the kidneys, ureters, urinary bladder, and urethra.
    • The kidneys filter waste products from the blood and produce urine.
    • Urine passes through the ureters to the urinary bladder, where it is stored until it is released through the urethra.
    • The kidneys also regulate electrolyte levels and maintain acid-base balance in the body.

    Artificial Kidney (Hemodialysis)

    • Artificial kidney (hemodialysis) is a treatment for kidney failure, where a machine takes over the function of the kidneys to remove waste products from the blood.

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    This quiz covers the components of a cell, including the plasma membrane, cytoplasm, nucleus, mitochondria, endoplasmic reticulum, ribosomes, and lysosomes. Test your knowledge of cell biology and organelle functions!

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