Cells: Structure and Function Quiz
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Questions and Answers

What is the primary difference between eukaryotic and prokaryotic cells?

Eukaryotic cells have a nucleus that encloses their DNA, while prokaryotic cells do not have a nucleus.

List three organelles that are present in plant cells but absent in animal cells.

Chloroplasts, a cell wall, and a large vacuole are present in plant cells but not in animal cells.

Explain the process of mitosis and its significance in cellular biology.

Mitosis is the process of cell division where chromosomes are copied and separated, resulting in two identical daughter cells. It is essential for growth, repair, and asexual reproduction.

What is the role of stem cells in the development of multicellular organisms?

<p>Stem cells are undifferentiated cells that have the potential to specialize into various types of cells during development.</p> Signup and view all the answers

Describe how magnification is calculated in microscopy.

<p>Magnification is calculated by dividing the image size by the object size.</p> Signup and view all the answers

What distinguishes a scanning electron microscope (SEM) from a transmission electron microscope (TEM)?

<p>A SEM allows electrons to bounce off the surface of the specimen, while a TEM passes electrons through the specimen.</p> Signup and view all the answers

How do gametes differ from somatic cells in terms of chromosome number?

<p>Gametes have half the number of chromosomes (23 each) compared to somatic cells, which have 46 chromosomes.</p> Signup and view all the answers

What is the importance of the cell wall in plant cells?

<p>The cell wall provides structural support and rigidity to plant cells.</p> Signup and view all the answers

What is the lock and key model in relation to enzymes?

<p>The lock and key model suggests that the active site of an enzyme is shape-specific, allowing only a specific substrate to fit and bind.</p> Signup and view all the answers

Describe what happens during enzyme denaturation.

<p>Denaturation involves the loss of an enzyme's 3D shape, which can be triggered by high temperatures or extreme pH levels, rendering it inactive.</p> Signup and view all the answers

In the enzyme practical mentioned, why is it important to test samples with iodine solution?

<p>Testing samples with iodine solution allows us to determine the presence or absence of starch, indicating whether the amylase has successfully broken it down.</p> Signup and view all the answers

What role do alveoli play in the human respiratory system?

<p>Alveoli are tiny air sacs where gas exchange occurs, facilitating the transfer of oxygen into the blood and carbon dioxide out of the blood.</p> Signup and view all the answers

Explain the difference between arteries and veins.

<p>Arteries carry oxygenated blood away from the heart and have thick walls to withstand high pressure, while veins carry deoxygenated blood back to the heart and have thinner walls with valves.</p> Signup and view all the answers

What are the characteristics of malignant tumors?

<p>Malignant tumors are characterized by uncontrolled cell growth and the ability to invade and spread to other parts of the body.</p> Signup and view all the answers

How does atherosclerosis affect blood flow?

<p>Atherosclerosis leads to the buildup of fat deposits in blood vessels, which restricts blood flow and can result in serious cardiovascular issues.</p> Signup and view all the answers

What is the primary difference between Type 1 and Type 2 Diabetes?

<p>Type 1 Diabetes is an autoimmune condition present at birth where the pancreas produces little to no insulin, while Type 2 Diabetes usually develops over time due to insulin resistance.</p> Signup and view all the answers

What does correlation mean in a scientific context?

<p>Correlation refers to a relationship between two factors where a change in one corresponds to a change in the other without implying a cause-and-effect relationship.</p> Signup and view all the answers

Identify one risk factor for developing cancer and explain its significance.

<p>Smoking is a significant risk factor for developing cancer because it introduces carcinogens into the body, which can lead to cellular mutations.</p> Signup and view all the answers

What are the four bases that make up DNA, and which bases pair together?

<p>The four bases are adenine (A), thymine (T), cytosine (C), and guanine (G). A pairs with T, and C pairs with G.</p> Signup and view all the answers

Define a gene in the context of DNA and protein synthesis.

<p>A gene is a sequence of DNA triplets that codes for a specific protein.</p> Signup and view all the answers

How does osmosis differ from diffusion?

<p>Osmosis is the movement of water molecules across a semi-permeable membrane from high to low water concentration, while diffusion is the movement of particles from high to low concentration.</p> Signup and view all the answers

Describe the concept of limiting factors in photosynthesis.

<p>A limiting factor is any condition that restricts the rate of photosynthesis, even if other factors are optimal.</p> Signup and view all the answers

What is the primary difference between aerobic and anaerobic respiration?

<p>Aerobic respiration requires oxygen and produces more energy, while anaerobic respiration occurs without oxygen and produces less energy, often resulting in lactic acid.</p> Signup and view all the answers

What role do platelets play in the body’s defense against pathogens?

<p>Platelets help clot blood to prevent infections by sealing wounds.</p> Signup and view all the answers

Explain how guard cells function in leaf gas exchange.

<p>Guard cells control the opening and closing of stomata, regulating gas exchange and water loss.</p> Signup and view all the answers

What is the purpose of antibiotics in medicine?

<p>Antibiotics kill bacteria or inhibit their growth, helping to treat bacterial infections.</p> Signup and view all the answers

Identify the two main types of cells involved in the immune response and their functions.

<p>Phagocytes engulf and destroy pathogens, while lymphocytes produce antibodies that target specific pathogens.</p> Signup and view all the answers

In what way does temperature affect enzyme activity?

<p>Temperature affects enzyme activity by increasing reaction rates up to an optimum point, after which high temperatures can denature the enzyme.</p> Signup and view all the answers

What is the function of xylem and phloem in plants?

<p>Xylem transports water upwards, while phloem transports sugars and other substances throughout the plant.</p> Signup and view all the answers

How can the build-up of lactic acid during anaerobic respiration be described?

<p>The build-up of lactic acid creates an 'oxygen debt' that must be paid off during recovery through oxygen intake.</p> Signup and view all the answers

What occurs during the practical investigation of osmosis using potato cylinders?

<p>Potato cylinders are placed in sucrose solutions, and changes in mass indicate whether water has osmosed into or out of the potato.</p> Signup and view all the answers

Describe how the process of photosynthesis is represented in a chemical equation.

<p>Photosynthesis is represented as Light + carbon dioxide + water → glucose + oxygen.</p> Signup and view all the answers

Study Notes

Cells

  • Eukaryotic cells possess a nucleus enclosing their DNA, examples include plant and animal cells.
  • Animal cells contain a nucleus, cytoplasm, mitochondria, ribosomes, and a cell membrane.
  • Plant cells, in addition to the components of animal cells, have a cell wall, a vacuole, and chloroplasts.
    • The cell wall, composed of cellulose, lends rigidity to the cell.
    • The vacuole is a large, fluid-filled sac, storing sap.
    • Chloroplasts house chlorophyll, the green pigment for photosynthesis.
  • Prokaryotic cells lack a nucleus; their DNA is a plasmid (circular DNA). Bacteria are prokaryotic.
  • Mitosis duplicates and separates chromosomes, forming two identical daughter cells. Humans have 23 chromosome pairs (46 total).
  • Gametes (sperm and egg) possess half the number of chromosomes (23 each) produced by meiosis.
  • Meiosis involves chromosome duplication and exchange before dividing, resulting in four genetically unique daughter cells.
  • Stem cells are undifferentiated cells that specialize into various cell types during development, such as brain or cheek cells.
  • Tissues are groups of similar cells performing a specific function, such as heart or lung tissue.
  • Organs comprise different tissues working together for a specific function, for instance, the heart or lungs.

Microscopy

  • Microscope magnification is calculated by dividing the image size by the object size.
  • Units of measurement include:
    • Nanometer (nm): one billionth of a meter (10⁻⁹ m).
    • Micrometer (µm): one millionth of a meter (10⁻⁶ m).
  • Unit conversions:
    • Divide by 1000 to convert nm to µm.
    • Divide by 1000 to convert µm to mm.
  • Light microscopes display cells but not organelles.
  • Electron microscopes utilize electrons for higher resolution, visualizing organelles and cellular structures.
    • Transmission electron microscopes (TEM) permit electrons to pass through the specimen.
    • Scanning electron microscopes (SEM) use electrons bouncing off the specimen's surface.

DNA and Protein Synthesis

  • DNA consists of four bases: adenine (A), thymine (T), cytosine (C), and guanine (G), following the A-T and C-G pairing rules.
  • A triplet is three DNA bases coding for a specific amino acid.
  • Amino acids are the components of proteins.
  • A gene is a DNA triplet sequence specifying a particular protein.
  • Protein synthesis creates proteins based on DNA instructions.

Diffusion and Osmosis

  • Diffusion moves particles from high to low concentration, following the concentration gradient, a passive process.
  • Osmosis involves water movement across a semi-permeable membrane from high to low water concentration, also a passive process.
  • Osmosis practical: Different sucrose solutions impact potato cylinders' weights, reflecting water movement.
  • Active transport moves substances against their concentration gradient, requiring energy.
  • Carrier proteins facilitate molecule transport across the cell membrane.

Bioenergetics

  • Respiration releases energy from glucose.
  • Aerobic respiration needs oxygen: Glucose + oxygen → carbon dioxide + water + energy.
  • Anaerobic respiration, without oxygen, converts glucose to lactic acid, releasing less energy.
  • Oxygen debt accumulates lactic acid during anaerobic respiration, needing oxygen for breakdown.
  • Photosynthesis uses light, carbon dioxide, and water to produce glucose and oxygen. Light + carbon dioxide + water → glucose + oxygen.
  • Photosynthesis factors include:
    • Light intensity: Increases photosynthesis up to a certain point.
    • Temperature: Optimal temperature enhances photosynthesis, becoming slower at too high or too low temperatures due to enzyme denaturation.
    • Carbon dioxide concentration: Higher concentrations boost photosynthesis up to a limit.
  • Limiting factors restrict processes even with optimal other factors.
  • Starch is a carbohydrate for plant energy storage.
  • Cellulose supports plant structures.
  • Lipids (fats and oils) store plant energy.
  • Food tests include:
    • Starch: Iodine turns purple with starch.
    • Fats: Ethanol becomes cloudy with fats.
    • Glucose: Benedict's solution changes from blue to orange with glucose.
    • Proteins: Biuret reagent changes from blue to purple with proteins.

Infection and Response

  • Infectious diseases originate from pathogens (bacteria, viruses, fungi, protists).
  • Defenses against pathogens include:
    • Skin: A barrier to prevent pathogen entry.
    • Platelets: Aid in blood clotting to prevent infections.
    • Cilia: Move mucus and pathogens in the trachea.
    • Mucus: Traps pathogens.
    • Stomach acid: Kills pathogens.
    • White blood cells:
      • Phagocytes: Engulf and destroy pathogens.
      • Lymphocytes: Produce antibodies binding to pathogen antigens.
  • Antibodies are proteins that target pathogen antigens.
  • Antigens stimulate the immune system.
  • Vaccination exposes the body to weakened or dead pathogens, prompting antibody production.
  • Antibiotics kill or inhibit bacterial growth.
  • Antibiotic resistance results from bacterial mutations.
  • Drug development encompasses: discovery, development, animal trials, blind and double-blind human trials, manufacturing, and long-term review.

Plant Organization

  • Root hair cells maximize water and nutrient absorption due to their large surface area.
  • Leaf components include:
    • Waxy cuticle: Prevents water loss.
    • Upper epidermis: Allows light passage.
    • Palisade mesophyll: Contains chloroplasts for photosynthesis.
    • Spongy mesophyll: Enables gas exchange.
    • Guard cells: Regulate stomata opening/closing.
    • Stomata: Leaf pores for gas exchange.
  • Stem components include:
    • Xylem: Transports water upwards (dead cells).
    • Phloem: Transports sugars and substances (living cells).
  • Transpiration is water vapor loss from leaves through stomata.
  • Transpiration factors include:
    • Temperature: Higher temperature increases transpiration.
    • Wind (airflow): Higher airflow increases transpiration.
    • Humidity: Higher humidity decreases transpiration.

Enzymes

  • Enzymes are biological catalysts (proteins) speeding up chemical reactions.
  • Enzymes' active sites bind to substrates.
  • Substrates are the molecules enzymes act upon.
  • The lock-and-key model describes the precise fit of enzymes to substrates.
  • Denaturation is the loss of enzyme shape due to high temperatures or extreme pH.
  • Enzyme practical involves exploring pH effects on enzyme activity (e.g., amylase and starch breakdown).

Human Gas Exchange and Circulation

  • Lungs are the main gas exchange organs.
    • Trachea: The windpipe .
    • Bronchi: Two tubes branching from the trachea.
    • Bronchioles: Smaller tubes branching off the bronchi.
    • Alveoli: Tiny air sacs for gas exchange.
  • Capillaries surround alveoli for gas exchange.
  • The heart pumps blood.
    • Right atrium receives deoxygenated blood from the body.
    • Right ventricle pumps deoxygenated blood to the lungs.
    • Left atrium receives oxygenated blood from the lungs.
    • Left ventricle pumps oxygenated blood to the body.
  • A double circulatory system has two loops:
    • Pulmonary circulation: Heart to lungs to heart.
    • Systemic circulation: Heart to body to heart.
  • Arteries carry blood away from the heart (thick walls due to high pressure).
  • Veins carry blood towards the heart (thin walls).
  • Veins contain valves to prevent backflow.
  • Capillaries let oxygen and carbon dioxide exchange.
  • Red blood cells' hemoglobin carries oxygen.
  • Carbon dioxide dissolves in plasma.

Blood Vessels

  • All arteries carry oxygenated blood, except for the pulmonary artery, which carries deoxygenated blood to the lungs.
  • Veins have thin walls and carry deoxygenated blood back to the heart.
  • Veins contain valves to prevent the backflow of blood.
  • Capillaries are tiny blood vessels that allow oxygen and carbon dioxide to exchange between cells and blood.
  • Oxygen binds to hemoglobin in red blood cells.
  • Carbon dioxide dissolves in plasma, the straw-colored liquid blood cells swim in

Communicable and Non-Communicable Diseases

  • Communicable diseases arise from pathogens (viruses, bacteria, etc.).
  • Non-communicable diseases are not infectious.

Atherosclerosis and Coronary Heart Disease (CHD)

  • Atherosclerosis involves fat deposits in blood vessels, hindering blood flow.
  • CHD is atherosclerosis affecting heart-surrounding vessels.

Aneurysms

  • Aneurysms are artery bulges that can rupture.
  • Some people are born with aneurysms.

Diabetes

  • Diabetes is characterized by insufficient insulin for blood glucose regulation.
  • Type 1 diabetes is present from birth.
  • Type 2 diabetes develops over time.

Cancer

  • Cancer is uncontrolled cell growth from mutated cells.
  • Benign tumors remain localized and are often less harmful.
  • Malignant tumors spread, posing harm.

Risk Factors for Diseases

  • Diet and smoking affect disease risk.
  • Drugs, UV light (skin cancer), and lack of exercise are also risk factors.
  • Carcinogens raise cancer risk.

Correlation and Causation

  • Correlation describes a relationship between factors; change in one factor corresponds with change in the other.
  • Causation is where one factor directly causes change in another.
  • Correlation doesn't imply causation; research is needed for causation proof.

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Test your knowledge on the various types of cells, including eukaryotic and prokaryotic cells. Explore the key components of animal and plant cells, as well as the processes of mitosis and meiosis. This quiz will cover essential concepts related to cellular biology.

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