Biology Quiz: Plant Transpiration and Heart Function
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Questions and Answers

Which of the following is NOT a function of transpiration in plants?

  • Cooling the plant through evaporation
  • Directly converting sunlight into chemical energy (correct)
  • Providing structural support to leaves and stems
  • Aiding in the uptake of mineral ions

    • Mature xylem vessels contain living cell contents to facilitate water transport.

    False (B)

    What two structural components provide strength and rigidity to xylem vessel walls?

    cellulose and lignin

    The evaporation of water from plant leaves is the primary driving force behind the movement of water through ______ vessels.

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

    Match the adaptation of xylem vessels with its corresponding function.

    <p>Non-living cells in mature vessels = Unimpeded water flow Lignin in cell walls = Resistance to low internal pressures Cohesive property of water = Water transport under tension</p> Signup and view all the answers

    What is the primary function of the septum in the heart?

    <p>To prevent the mixing of blood between the left and right sides of the heart. (C)</p> Signup and view all the answers

    The sinoatrial node (SAN), or pacemaker, is located in the wall of the left atrium.

    <p>False (B)</p> Signup and view all the answers

    Describe the sequence of events following the initiation of a heartbeat by the pacemaker.

    <p>The pacemaker initiates a heartbeat by sending a wave of excitation across the atria, causing atrial contraction. The electrical impulse then travels down to the base of the ventricles, spreading upwards across the ventricular walls, leading to ventricular contraction.</p> Signup and view all the answers

    The two blood vessels that bring blood to the heart are the vena cava and the ______.

    <p>pulmonary vein</p> Signup and view all the answers

    What determines whether a valve in the heart opens or closes?

    <p>The relative pressure of blood on either side of the valve. (B)</p> Signup and view all the answers

    Which of the following best describes the role of elastic tissue in the artery walls?

    <p>Maintains blood pressure by stretching and recoiling. (D)</p> Signup and view all the answers

    Arteries transport blood towards the heart.

    <p>False (B)</p> Signup and view all the answers

    What is the function of the endothelial layer in arteries?

    <p>reduces friction for free blood flow</p> Signup and view all the answers

    The middle layer of the artery wall contains smooth muscle cells and a thick layer of ______ tissue.

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

    Why do arteries have a narrow lumen?

    <p>To maintain high blood pressure. (B)</p> Signup and view all the answers

    Match the artery wall layer with its primary function:

    <p>Endothelial Layer = Reduces friction for free blood flow Middle Layer = Controls lumen diameter and regulates blood pressure Outer Layer = Protects blood vessels from damage</p> Signup and view all the answers

    Which component of the outer layer of artery walls protects against over-stretching?

    <p>Collagen (C)</p> Signup and view all the answers

    How do arteries closer to the heart differ in composition from those further away?

    <p>More elastic tissue and less smooth muscle</p> Signup and view all the answers

    Why is the middle layer of veins much thinner compared to arteries?

    <p>Because veins do not need to maintain or withstand high pressure. (D)</p> Signup and view all the answers

    Veins transport blood away from the heart.

    <p>False (B)</p> Signup and view all the answers

    What structural adaptation in veins prevents the backflow of blood?

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

    Capillaries converge to form ______, which deliver blood to veins.

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

    How does the movement of skeletal muscles aid in venous blood flow?

    <p>By compressing the veins, pushing blood towards the vena cava. (B)</p> Signup and view all the answers

    Which of the following is the primary reason for veins having a wide lumen?

    <p>To maximize the volume of blood that can flow at any one time. (C)</p> Signup and view all the answers

    The walls of the veins are rigid and inflexible.

    <p>False (B)</p> Signup and view all the answers

    Match each structural feature of veins with its function:

    <p>Thin middle layer = Does not need to withstand high pressure Valves = Prevents backflow of blood Wide lumen = Maximizes blood volume flow Flexible walls = Allows muscles to compress the vein</p> Signup and view all the answers

    Why is the intrinsic rhythm of the heart significant?

    <p>It enables the heart to beat independently of external nervous stimuli. (A)</p> Signup and view all the answers

    The atrioventricular node (AVN) directly initiates the contraction of the ventricles.

    <p>False (B)</p> Signup and view all the answers

    What structural feature prevents the wave of depolarisation from spreading directly from the atria to the ventricles and why is this important?

    <p>A region of non-conducting tissue. It delays the impulse, allowing the atria to finish contracting before the ventricles contract.</p> Signup and view all the answers

    The wave of excitation is carried down the septum by the bundle of ______ and spreads around the ventricles via the ______ fibers.

    Signup and view all the answers

    What is the primary function of phloem tissue in plants?

    <p>Transporting organic compounds, particularly sucrose, from sources to sinks. (D)</p> Signup and view all the answers

    Sieve tube cells have a large amount of cytoplasm and many organelles to facilitate efficient transport.

    <p>False (B)</p> Signup and view all the answers

    What is the role of companion cells in relation to sieve tubes?

    <p>Companion cells aid with the loading and unloading of dissolved substances into sieve tubes.</p> Signup and view all the answers

    Sieve tube cells are separated by perforated ______ plates which allow the passage of assimilates.

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

    Match the cell type with its main function in phloem tissue:

    <p>Sieve tube cells = Form a continuous tube for the flow of phloem sap, allowing the transport of assimilates. Companion cells = Aid with the loading and unloading of dissolved substances, providing ATP for active transport. Plasmodesmata = Bridges of cytoplasm that link sieve tubes and companion cells.</p> Signup and view all the answers

    What is the primary function of the sinoatrial node (SAN) in the cardiac cycle?

    <p>To initiate a wave of depolarisation that causes the atria to contract. (D)</p> Signup and view all the answers

    The heart requires external stimulus from the nervous system to beat.

    <p>False (B)</p> Signup and view all the answers

    What structural feature prevents the immediate spread of depolarization from the atria to the ventricles and why is this delay important?

    <p>A region of non-conducting tissue prevents the immediate spread of depolarization. This delay allows the atria to finish contracting before the ventricles begin.</p> Signup and view all the answers

    The wave of excitation is carried down the septum by the bundle of ______ and spreads around the ventricles via the Purkyne fibres.

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

    Match each stage in the cardiac cycle sequence with its corresponding event:

    <p>Sinoatrial node sends out a wave of excitation = Stage 1 Atria contract = Stage 2 Atrioventricular node sends out a wave of excitation = Stage 3 Purkyne tissue conducts the wave of excitation = Stage 4 Ventricles contract = Stage 5</p> Signup and view all the answers

    Flashcards

    Capillaries

    Small blood vessels with a narrow lumen and one cell thick walls that facilitate diffusion between blood and cells.

    Function of arteries

    Transport blood away from the heart at high pressure to body tissues.

    Artery wall layers

    Consists of three layers: endothelial, smooth muscle and elastic tissue, and outer collagen layer.

    Endothelial layer

    The innermost layer of arteries that is one cell thick, smooth, and reduces friction.

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    Smooth muscle layer in arteries

    Middle layer that strengthens arteries and regulates lumen diameter to control blood pressure.

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    Elastic tissue function

    Helps maintain blood pressure by stretching and recoiling to manage fluctuations from heartbeats.

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    Outer layer of arteries

    Made mostly of collagen and elastic fibres that protect vessels from damage and over-stretching.

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    Narrow lumen of arteries

    Helps maintain high blood pressure by restricting blood flow area, increasing velocity.

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    Transpiration

    The movement of water through xylem due to evaporation from leaves.

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    Cohesion and Adhesion

    Water molecules stick to themselves (cohesion) and to other surfaces (adhesion).

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    Xylem Vessels

    Long tubes in plants that transport water and minerals from roots to leaves.

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    Lignin

    A polymer that strengthens the walls of xylem vessels and allows them to withstand pressure.

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    Evaporative Cooling

    Cooling of a plant through water vapor loss during transpiration.

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    Septum

    A wall that prevents blood mixing between the heart's sides.

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    Sinoatrial Node

    The pacemaker of the heart that initiates the heartbeat.

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    Atrial Contraction

    The event triggered by the pacemaker causing the atria to contract.

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    Valves of the heart

    Structures that keep blood flowing in one direction.

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    Atrioventricular Valves

    Valves preventing blood from flowing back into the atria from the ventricles.

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    Function of veins

    Veins transport blood to the heart at low pressure.

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    Structure of veins

    Veins have thinner walls compared to arteries and a flexible structure.

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    Lumen of veins

    Veins have a wide lumen to maximize blood flow.

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    Veins and pressure

    Veins do not need to withstand high pressure unlike arteries.

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    Valves in veins

    Valves in veins prevent backflow of blood under low pressure.

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    Venules

    Venules are small veins that receive blood from capillaries.

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    Skeletal muscle movement

    Skeletal muscle contractions help push blood through veins.

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    Diffusion in capillaries

    Capillaries have one-cell thick walls for efficient diffusion.

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    Myogenic heartbeat

    The heart beats intrinsically without external nervous stimulation.

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    Sinoatrial node (SAN)

    A group of cells in the right atrium that initiates heartbeat.

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    Atrioventricular node (AVN)

    Conducting tissue that relays excitation from atria to ventricles.

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    Purkyne fibres

    Conducting fibres that spread the excitation through ventricles.

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    Cardiac cycle stages

    Sequence of events in heart contraction starting with SAN.

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    Phloem function

    Transports organic compounds, especially sucrose, from sources to sinks in plants.

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    Sieve tube elements

    Cells that form a continuous tube for phloem sap, separated by sieve plates.

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    Companion cells

    Specialized cells aiding in loading/unloading substances into sieve tubes, rich in mitochondria.

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    Plasmodesmata

    Cytoplasmic connections between sieve tubes and companion cells that aid transport.

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    Phloem tissue composition

    Made of sieve tube elements and companion cells that work together for transport.

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    Study Notes

    Blood Vessels

    • The circulatory system contains various types of blood vessels: arteries, arterioles, capillaries, venules, and veins.
    • Each blood vessel type has a specific structure related to its function.

    Capillaries

    • Capillaries are the exchange surface in body tissues.
    • Their walls are one cell thick (endothelial cells), minimizing diffusion distance for substances like oxygen and carbon dioxide.
    • Some capillaries have gaps (fenestrations) allowing plasma to leak out, forming tissue fluid.

    Arteries

    • Arteries carry blood away from the heart at high pressure.
    • Their walls have three layers: an inner endothelium (smooth for reduced friction), a middle layer of thick smooth muscle and elastic tissue.
    • Elastic tissue helps maintain pressure, while smooth muscle regulates blood flow and pressure.
    • Arteries have a narrow lumen compared to their thickness to maintain high pressure.

    Veins

    • Veins carry blood back to the heart at low pressure.
    • Their walls have thinner smooth muscle and elastic tissue compared to arteries enabling vessels to be more compliant.
    • Veins have a wider lumen compared to their thickness to maximize blood flow.
    • Veins have valves to prevent backflow of blood.

    Measuring Pulse Rate

    • Pulse rate can be measured by placing two fingers on the radial or carotid artery.
    • Count the number of pulses felt for 60 seconds.
    • Alternatively, count for 30 seconds and multiply by 2.
    • Do not use your thumb to take a pulse.

    Coronary Heart Disease

    • Coronary heart disease results from the narrowing of the coronary arteries due to a blockage.
    • This blockage can be caused by atherosclerosis, where fatty deposits (atheromas) build up under the endothelium.
    • Atherosclerosis is often the result of high blood pressure.

    Evaluating Epidemiological Data

    • Claims about lifestyle risk factors and heart disease are often based on correlation, not causation.
    • Epidemiological studies examine large populations, but these studies cannot determine cause-and-effect.
    • Results must be statistically significant, and must be able to be replicated in controlled studies and with broader populations.

    The Transpiration Stream

    • Water evaporates from leaves during transpiration, creating a negative pressure in the xylem.
    • This pull is transmitted through the plant due to cohesion between water molecules.
    • This process is sometimes called the cohesion-tension theory.

    Adaptations of Xylem Vessels

    • Xylem vessels are long, continuous, hollow tubes.
    • They have thickened walls (cellulose and lignin) to withstand tension.
    • Pits in the walls allow water to move sideways between vessels.

    Dicotyledonous Stem Structure

    • The stem has several tissues including the epidermis (outer layer), cortex (beneath the epidermis), and pith (central region).
    • Vascular tissue is arranged in a ring of vascular bundles.
    • Dicotyledonous stems have different types of tissues including the vascular bundles or the xylem and phloem arranged in a ring, the cortex, and the pith.
    • Plan diagrams should not contain shading, and should include annotations giving functions.

    Dicotyledonous Root Structure

    • Xylem is centrally located in the root, in a cross-shaped structure.
    • Phloem tissue is located between the cross "arms" of the xylem.
    • The cortex and epidermis are regions for storage and protection.

    Tissue Fluid

    • Plasma filters out of the capillaries at the arterial end, forming tissue fluid.
    • Tissue fluid surrounds body cells for exchange of materials.
    • The proteins and cells in the blood are too large to leave the capillaries and remain in the blood.
    • Pressure filtration and reuptake of fluid balance formation of tissue fluid.
    • At the venous end most of the fluid re-enters the capillaries via osmosis and pressure differences.

    Circulatory Systems (HL)

    • Bony fish have single circulation (blood passes through the heart once).
    • Mammals have double circulation (blood passes through the heart twice).
    • Double circulation allows a higher blood pressure and helps to keep oxygenated and deoxygenated blood separate.

    The Mammalian Heart

    • The four-chambered heart has two atria and two ventricles to separate oxygenated and deoxygenated blood.
    • Valves ensure unidirectional blood flow.
    • The Sinoatrial node (SAN) is the pacemaker and initiates the heartbeat, coordinating contraction.

    The Cardiac Cycle

    • The cardiac cycle consists of atrial systole, ventricular systole, and diastole.
    • The wave of depolarisation spreads across the heart in a coordinated manner (contraction or relaxation of the chambers).
    • Pressure and volume changes drive the opening and closing of valves during the cycle.

    Coronary Arteries

    • Coronary arteries supply the heart muscle with oxygenated blood.
    • These arteries have branched to the heart muscle.

    The Roots and Water Transport

    • Transpiration creates a negative pressure in the xylem, pulling water up the plant.
    • Root pressure can also help move water upwards, especially in conditions where transpiration is low
    • The movement of water can be due to the action of the root cells or due to the evaporative pull within plant leaves

    Translocation in Plants

    • Translocation is the movement of organic substances in the phloem (organic compounds or assimilates).
    • Sources are regions producing organic compounds (sugars), such as mature leaves, whereas sinks are regions that use compounds (such as growing tissues).
    • The movement of organic compounds through the phloem is an active process, facilitated by the high hydrostatic pressure at the source and the low hydrostatic pressure at the sink.
    • Sieve tube cells and companion cells are crucial components of phloem tissue facilitating translocation.

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    Description

    Test your knowledge on the functions of transpiration in plants and the structural components of xylem vessels. Additionally, explore the heart's role, including the sinoatrial node and blood vessels that lead to the heart. This quiz covers key concepts in plant biology and human anatomy.

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