5.5 Plant and Animal Responses

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  • Created by: elbungay1
  • Created on: 25-03-19 14:24
What are the chemical responses of a plant?
Tannins: toxic to microorganisms and larger herbivores, prevent pathogen entering roots. Alkaloids: feeding deterrent, tasting bitter. Pheromones: affect behaviour or physiology other other organism
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What is a tropism? Give some examples
Directional growth responses of a plant. Include phototropism (shoots grow towards light, positively phototropic), geotropism (roots grow towards pull of gravity, water intake and stability). Chemotropism and Thigmotropism
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What's the difference between positive and negative tropism?
If a plant grows towards a stimulus, it is positively tropic response. If a plant responds away from a stimulus, it is negative tropic response.
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Give an example of a nastic response
Non-directional response to a stimuli, mimosa pudica responds to touch by folding of the leaves, examples of thigmonasty
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What is the role of Auxins and describe its properties
Plant hormones which are responsible for regulating plant growth, high concentrations inhibit later bud growth, promotes apical dominance
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What are Gibberellins
Plant hormones which are responsible for control of stem elongation (by cell elongation and cell divison) and seed germination
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What are commercial uses of Auxins
Part of rooting powder which is used when taking cuttings of plants. Promotes growth of seedless fruit. Kills weeds by causing excessive stem growth until plant cannot support itself
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What is the commercial use of Cytokinins
Delay leaf senescence, prevent yellowing of lettuce leaves. Used in mass production of plants as they promote bud and shoot growth
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What is the commercial use of Gibberellins?
Delay senescence in citrus fruit, improve shape of apples, elongate grape stalks so fruit separate and grow bigger. Speeds up alcohol brewing, stimulates growth in sugar cane, speeds up plant breeding
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What are the commercial uses of Ethene gas?
Speeding up ripening in apples, tomatoes and citrus fruit. Promoting fruit drop in cotton, cherry and walnuts. Prevent self pollination of cucumbers, increasing yield. Without ethene, delays fruit ripening, keeping fruits fresh
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Describe the divisions of the nervous system
Split into CNS and PNS. The PNS is divided into the motor system and the sensory system. The motor system is divided into somatic nervous system and autonomic nervous system
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What is the difference between autonomic and somatic nervous systems?
Somatic nervous system consist of motor neurones that conduct action potential from CNS to effectors under conscious control, e.g. skeletal muscles. The autonomic system is not under voluntary control e.g. glands, cardiac muscle and smooth muscle
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What divisions of the autonomic nervous system are there?
Sympathetic system which prepares the body for activity and the parasympathetic system which conserves energy
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Describe differences in effect of sympathetic and parasympathetic systems
S - increases heart rate, dilates pupils, increases ventilation rate, reduces digestive activity, ******. PS - decreases heart rate, constricts pupils, reduces VR, increases DA, sexual arousal
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Describe the sections of the human brain
Cerebrum (conscious thought, memory), cerebellum (movement, balance), Hypothalamus pituitary comples (homeostatic responses), medulla oblongata (autonomic responses)
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What is a reflex action?
Responses to changes in the environment that do not involve any processing in the brain to coordinate movement.
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Describe the knee jerk reflex
Reflex action that straightens the leg when the tendon below the knee cap is tapped. Spinal reflex - nervous pathway that goes through spinal cord. Fast as only involves one synapse between sensory and motor neurone
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How is a fight or flight response coordinated?
Inputs feed into sensory centres in cerebrum and the cerebrum passes signals to the association system. If a threat is recognised, the cerebrum stimulates hypothalamus, hypothalamus increases activity in sympathetic system and releases hormones
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Why is the human heart described as myogenic?
It can initiate its own beat at regular intervals even if disconnected from autonomic nervous system
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Where is the cardiovascular centre found?
Medulla oblongata
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How do nerves affect the rate of heart contractions?
Action potentials down a sympathetic nerve (accelerans nerve) releases noradrenaline at SAN, increasing heart rate. Action potentials sent down vagus nerve release ACh which reduces heart rate
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What sensory receptors send information to cardiovascular centre to change heart rate?
Stretch receptors in muscles of limbs, increased heart rate due to higher O2 demand. Chemoreceptors monitor pH, if too acidic increased heart rate to expel CO2. Concentration of CO2 falls decreases heart rate. Stretch receptors in Cartoid Sinus
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What are the three types of muscle
Cardiac muscle (found in walls of heart), involuntary muscle (smooth muscle that contracts without conscious control), Skeletal Muscle (muscle under voluntary control).
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Describe the stimulation of contraction at the Neurotransmitter Junction
Action potnetial arrives at the end of axon and open calcium ion channels in the membrane. Calcium ions diffuse in adn vesicles of ACh fuse with membrane and release by exocytosis. ACh binds with receptors on sarcolemma, opens Na ions, depolarisation
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Describe the structure of contractile units of skeletal muscle, myofibrils
Thin filaments, actin, aligned to make up light band, held by Z line. Myosin make up dark band. Distance between Z lines is Sarcomere, functional unit of muscle.
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What is wound around Actin filaments?
Molecule of tropomyosin to which are attached globular molecule of troponin.
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Describe the structure of thick filaments?
Consists of a bundle of myosin molecules. Each myosin molecule has two protruding heads which stick out. The heads are mobile and can bind to actin, when binding sites are exposed.
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Describe how Calcium ions are released into sarcoplasm
Muscle is stimulates and action potential passes along the sarcolemma, down transverse tubules. Action potential reaches sarcoplasmic reticulum, which stores calcium ions and causes their release into sarcoplasm.
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Describe the role of Calcium Ions in muscle contraction
Calcium ions bind to troponin, causes conformational change, pulling tropomyosin aside,exposing binding sites. Myosin heads move to actin, forming cross bridge, myopsin head slides actin filament past myosin filament. Myosin head detaches and rebinds
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What is the role of ATP in muscle contraction?
Power stroke (sliding actin filament across myosin filament) uses ATP to form ADP and P. After power stroke, a new ATP molecule attaches to the myosin head, breaking cross-bridge. ATP is hydrolysed as mysoin head returns to original position.
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How is the supply of ATP maintained?
Aerobic respiration in mitochondria. Anaerobic respiration in sarcoplasm of muscle tissue. Creatine phosphate can transfer phosphate grousp to ADP creating ATP very rapidly, it acts as a reserve store of phosphate groups
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Card 2

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What is a tropism? Give some examples

Back

Directional growth responses of a plant. Include phototropism (shoots grow towards light, positively phototropic), geotropism (roots grow towards pull of gravity, water intake and stability). Chemotropism and Thigmotropism

Card 3

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What's the difference between positive and negative tropism?

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Preview of the front of card 3

Card 4

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Give an example of a nastic response

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Card 5

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What is the role of Auxins and describe its properties

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