Fruit Ripening and Ethylene Senescence
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Questions and Answers

What is the role of statoliths in plants?

  • Activating pressure receptors in the shoot system
  • Indicating the direction of gravity in root cap cells (correct)
  • Promoting thigmomorphogenesis in plant stems
  • Initiating the gravitropic response in apical bud cells

    • What is the main characteristic of thigmomorphogenesis in young plants?

  • Increased leaf size
  • Enhanced flower production
  • Shorter height and thicker stems (correct)
  • Taller height and thinner stems

    • Which hormone is responsible for mediating thigmomorphogenesis in plants?

  • Ethylene (correct)
  • Auxin
  • Cytokinin
  • Gibberellin

    • What environmental factor triggers vernalization in plants?

    <p>Prolonged periods of low temperatures</p> Signup and view all the answers

    What is the purpose of plant defense systems against herbivores and pathogens?

    <p>Prevent infection and deter herbivory</p> Signup and view all the answers

    _______ Responses observed in plants include growth response and curvature of organs toward or away from a stimulus.

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

    _______ is a response to light in plants.

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

    _______ is a response to gravity in plants.

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

    _______ is a response to mechanical disturbance in plants.

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

    _______ is the process of producing flowers in plants.

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

    _______ is the programmed death of plant cells or organs.

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

    _______ is the process of fruits becoming sweeter and falling from the plant stem.

    <p>Fruit maturation and ripening</p> Signup and view all the answers

    _______ refers to a class of plant hormones that promotes cell elongation in stems and roots.

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

    The ______ pumps lower the pH in the cell wall, activating expansins

    <p>proton (H+)</p> Signup and view all the answers

    Expansins are enzymes that break hydrogen bonds between cellulose fibres, thus loosening the ______ wall

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

    With the cellulose loosened, the cell is free to absorb more ______, causing it to swell and elongate

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

    Auxin is involved in root formation and ______

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

    Cytokinins stimulate ______, which divides the cytoplasm of a parental cell into two daughter cells

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

    Cytokinins regulate growth by activating genes that keep the ______ cycle going, stimulating cell division

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

    Cytokinins are produced in actively growing tissues such as roots, ______, and fruits

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

    Cytokinins regulate growth by activating genes that keep the cell cycle going, stimulating ______ division

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

    The embryo releases ______ to the aleurone layer

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

    The aleurone layer secretes ______ to hydrolyze sugars in the endosperm

    <p>alpha-amylase</p> Signup and view all the answers

    Sugars are then absorbed by the ______, which initiates the embryo to grow

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

    ABA inhibits ______ (including inhibiting seed germination)

    <p>plant growth</p> Signup and view all the answers

    In some seeds, dormancy is broken when ABA is removed by heavy rain, light, or prolonged ______

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

    ABA is the primary internal signal that enables plants to withstand ______

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

    Plants produce ethylene in response to stresses such as drought, flooding, mechanical pressure, injury, and ______

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

    The effects of ethylene include response to fruit ripening, mechanical stress, senescence, and leaf ______

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

    Cytokinins work together with auxin to control cell division and differentiation, cytokinins alone have no ______ effect!

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

    Cytokinins, auxin, and other factors interact in the control of apical dominance, a terminal/apical bud’s ability to suppress the development of axillary/lateral buds so that the plant can grow ______

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

    If the terminal bud is removed, plants become bushier as lateral buds grow and develop into new ______

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

    Cytokinins delay the aging of some plant organs by inhibiting protein breakdown, stimulating RNA and protein synthesis, and assembling nutrients from surrounding ______

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

    If removed leaves from plant are dipped in cytokinin solution, they stay green much ______

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

    Gibberellins stimulate the growth of leaves and ______

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

    In many plants, both auxin and gibberellins must be present for fruit to ______

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

    After water is taken up by a dry seed (imbibition), gibberellins are released from the embryo signals to allow for seed ______

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

    Plants can sense and respond to information about light, gravity, pressure, and ______.

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

    Plants have the equivalent of a sense of smell and can perceive certain airborne ______.

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

    Plants have a sense of taste because their roots can detect nutrients in the ______.

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

    Sensory cells receive an external signal and change it into an intracellular ______.

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

    Sensory cells then send a signal to target cells in other parts of the plant ______.

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

    Target cells receive the signal and change their activity to produce an appropriate ______.

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

    Usually, a hormone is transported to the target cells, where it causes a physiological ______.

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

    In general, hormones control plant growth and development by affecting cell division, cell elongation, cell differentiation, and cell ______.

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

    What is the term for a growth response resulting in curvature of organs toward or away from a stimulus?

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

    What is the process of producing flowers in plants called?

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

    Which plant hormone promotes cell elongation in stems and roots?

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

    What is the programmed death of plant cells or organs called?

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

    Which plant hormone is responsible for fruit maturation and ripening?

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

    What is the term for the process of fruits becoming sweeter and falling from the plant stem?

    <p>Fruit maturation</p> Signup and view all the answers

    What is the process of developing a plant from a seed or spore after a period of dormancy?

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

    Which plant response refers to the inhibition of plant growth, including inhibiting seed germination?

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

    What is the role of proton pumps in the cell wall?

    <p>Lower the pH and activate expansins</p> Signup and view all the answers

    How do expansins affect the cell wall?

    <p>Loosen by breaking hydrogen bonds between cellulose fibers</p> Signup and view all the answers

    What is the main function of auxin in secondary growth?

    <p>Inducing cell division in the vascular cambium</p> Signup and view all the answers

    What is the primary function of cytokinins in cell division and differentiation?

    <p>Stimulate cytokinesis</p> Signup and view all the answers

    Where are cytokinins primarily produced in plants?

    <p>Actively growing tissues such as roots, embryos, and fruits</p> Signup and view all the answers

    How do cytokinins regulate growth?

    <p>Activating genes to stimulate cell division</p> Signup and view all the answers

    What happens to a cell when cellulose is loosened?

    <p>Absorb more water, swell, and elongate</p> Signup and view all the answers

    What is the effect of cytokinins and auxin working together in cell division and differentiation?

    <p>Control of apical dominance</p> Signup and view all the answers

    What hormone is responsible for slowing plant growth and inhibiting seed germination?

    <p>Abscisic acid (ABA)</p> Signup and view all the answers

    Which enzyme is secreted by the aleurone layer to hydrolyze sugars in the endosperm?

    <p>Alpha-amylase</p> Signup and view all the answers

    What is the primary internal signal that enables plants to withstand drought?

    <p>ABA (Abscisic acid)</p> Signup and view all the answers

    Which plant hormone is released in response to stresses like drought, flooding, and mechanical pressure?

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

    What triggers the breaking of dormancy in some seeds by removing ABA?

    <p>Heavy rain, light, or prolonged cold</p> Signup and view all the answers

    Which hormone is responsible for initiating the growth of the embryo in plants?

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

    What process involves the use of ethylene in response to mechanical stress, injury, and infection?

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

    In seed germination, what is the role of the scutellum after absorbing sugars?

    <p>Initiates the embryo to grow</p> Signup and view all the answers

    What triggers the ripening process in fruits?

    <p>A burst of ethylene production</p> Signup and view all the answers

    What is associated with apoptosis, the programmed destruction of plant cells or organs?

    <p>A burst of ethylene</p> Signup and view all the answers

    What controls leaf abscission in plants?

    <p>A change in the balance of auxin and ethylene</p> Signup and view all the answers

    What is the triple response induced by ethylene in plants?

    <p>Slowing of stem elongation, thickening of the stem, and horizontal growth</p> Signup and view all the answers

    What type of light receptors control stomatal opening, chlorophyll synthesis, and phototropism in plants?

    <p>Blue-light photoreceptors</p> Signup and view all the answers

    What class of light receptors control seed germination, shade avoidance, and induction of flowering in plants?

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

    What is the biologically active form of phytochrome?

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

    What process allows a growing shoot to avoid obstacles in its path?

    <p>Triple response induced by ethylene</p> Signup and view all the answers

    What are statoliths and how do they help plants in orienting their roots and shoots?

    <p>Statoliths are specialized amyloplasts that fall to the bottom of cells, indicating the direction of gravity. This helps plants orient their roots and shoots according to gravity.</p> Signup and view all the answers

    Explain thigmomorphogenesis in young plants and the role of ethylene in this process.

    <p>Thigmomorphogenesis is the change in form caused by mechanical disturbance, resulting in shorter plants with thicker stems. Ethylene mediates this response as a hormone.</p> Signup and view all the answers

    What environmental factor triggers vernalization in plants and what is the purpose of vernalization?

    <p>Prolonged periods of low temperatures, such as those in winter, trigger vernalization in plants. Vernalization induces flowering in response to cold conditions.</p> Signup and view all the answers

    How do plants defend against herbivores and pathogens? Explain the role of defense systems.

    <p>Plants use defense systems to deter herbivory, prevent infections, and combat pathogens. These defense systems help protect plants from external threats.</p> Signup and view all the answers

    What is the mechanism behind thigmotropism in plants?

    <p>Thigmotropism is the response to mechanical disturbance like touch and wind. It causes growth responses and curvature of organs towards or away from the stimulus.</p> Signup and view all the answers

    How do amyloplasts activate sensory proteins in plant cells?

    <p>The position of amyloplasts activates pressure receptors in the plasma membrane of cells. This activation triggers the gravitropic response in plants.</p> Signup and view all the answers

    Explain the role of ethylene in thigmomorphogenesis and its effects on plant morphology.

    <p>Ethylene mediates thigmomorphogenesis, causing plants to become shorter with thicker stems when mechanically disturbed. This adaptation is thought to prevent plants from being blown over in windy environments.</p> Signup and view all the answers

    Describe the process by which statoliths help plants respond to gravity.

    <p>Statoliths are dense amyloplasts that fall to the bottom of cells, indicating the downward direction. This activates pressure receptors, leading to the gravitropic response in plants.</p> Signup and view all the answers

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