5.1.5- Animal and Plant Responses Flashcards
where is the cerebrum in the brain?
the folded top part of the brain
what is the function of the cerebrum
Controls voluntary actions
Eg-learning, memory, personality and consciousness
where is the hypothalamus in the brain?
next to the piturity gland
What is the function of the hypothalamus?
Regulatory centre for osmoregulation and temperature balance
where is the cerebellum?
the swirly part at the bottom of the brain.
what is the function of the cerebellum?
Controls unconscious functions, such as balance, posture and non-voluntary movement.
Where is the medulla oblongata in the brain?
the stem at the bottom
What is the function of the medulla oblongata?
Used in autonomic control, eg- heart rate and breathing rate
Where is the puiturity gland?
next to the hypothalamus, bottom front
What is the function of the puiturity gland?
Stores and releases hormones that regulate many body functions.
What is the knee jerk reflex?
-spinal reflex
-doctors use to it to see how the nervous system is working.
-patella tapped so patella tendon stretches (stimulus)
-this initiates the reflex arc
-contraction of extensor muscle above thigh
-absense of reflex= cereballar disease
What is the blinking reflex?
-involuntary blinking
-it protects the eye from damage
What are the 3 types of muscle?
-skeletal muscle
-cardiac muscle
-smooth muscle
What is skeletal muscle?
-also known as voluntary/striated muscle
-regularly arranged so contracts in one direction
-long cylindrical multinucleate fibres.
-contracts quickly, fatigues quickly
-contraction controlled by the somatic nervous system
-short length of contraction
What is the function of the skeletal muscle?
To move the bones of the skeleton about the joints
What is the cardiac muscle?
-surrounds the heart
-single cylindrical branched cells, separated by intercalated discs
-each cell has own nucleus
-striated
-contracts quickly, does not fatigue
-contraction is controlled by the autonomic nervous system and the myogenic control
-intermediate length of contraction
What is the function of cardiac muscle?
Causes the heart to contract and relax, so it can pump blood around the body.
What is smooth muscle?
-spindle shaped, unstriated, single nucleus
-contracts slowly, fatigues slowly
-can remain contracted for a long time
-contraction is controlled by the autonomic nervous system
What is the function of the smooth muscle?
-peristalsis in the gut walk
-pupil dilation and constriction in the eye
-vasodilation and vasoconstriction in the arterioles.
What is a neuromuscular junction?
A specialised synapse which occurs at the end of a motor neurone, where it meets a muscle fibre
What is the order of action at a neuromuscular junction?
*in the pre-synaptic neurone, everything is the same as as a synapse.
-when neurotransmitter diffuses across membrane, it causes depolarisation, which travels along the muscle, and down the tubule
-this causes the sacroreticulum’s membrane to also depolarise, which releases calcium ions
-these calcium ions move into the myofibril, which begins the contraction of the muscle
What is the A band of a myofibril?
Where actin and myosin remain
What is the H zone of a myofibril?
Where only myosin occurs
What is the I band of a myofibril?
Where only actin occurs
What is the M line of a myofibril?
A protein which anchors the myosin filaments
What is the Z line of a myofibril?
A protein that anchors the actin filaments
In a myofibril, what are the widths of actin and myosin like?
Actin= thinner line
Myosin= thicker line
what are the two proteins present in a myofibril called?
actin and myosin
what do actin and myosin give a muscle?
give striated muscles their distinct banding
explain the structure of actin?
-each actin filament is made up of two actin molecules
-made up of globular beads
-the two actin molecules are coiled around each other (like strings of beads)
-tropomyosin and troponin
explain the structure of mysoin?
-each filament is made up of 200 myosin molecules
-each molecule has 2 protruding heads and a long tail
-the heads contain ATPase
-resting myosin heads are bound to ADP and Pi
what are the 8 stages of the sliding filament of muscle contraction?
-when an AP arrives at NMJ, SPR releases calcium ions
-calcium ions bind to troponin
-troponin changes shape
-troponin pulls tropomyosin away from actin binding sites
-myosin head binds to the actin binding site forming a cross-bridge
-myosin head bends 45 degrees, pulling actin filament (releasing bound ADP and Pi)
-ATP is used to break cross-bridge, when it binds to the myosin head, causing it to detach from the actin
-myosin head straightens so becomes free to form a new cross-bridge further along the actin. The hydrolysis of ATP that recocks the head, so it ready to bind again at original position
THIS REPEATS
when muscles contract, what regions gets shorter?
-sarcomere
-H zone
-I band
during muscle contraction, what happens to the Z lines?
they move closer to one another
during muscle contraction, what region stays the same?
A band
what are the 4 roles of ATP in muscle contraction?
-breaks the cross bridge, allowing the myosin head to reset
-actively transports calcium ions back into the sarcoplasmic reticulum when contraction stops
-relax= reacts with creatine to make creatine phosphate, which is used to maintain ATP supply in contracting
-protein synthesis (to make actin and myosin)
how does creatine phosphate maintain the supply of ATP during muscle contraction?
-acts as a reserve supply of phosphate, which is available immediately to combine with ADP reforming ATP.
-it is used for short bursts of vigorous exercise.
-during relaxation, it is replenished.
what are the survival importances of reflexes?
-fast, prevents harm
-doesn’t need to be learnt
-involuntary so free for more complex processes
-everyday actions
what is the difference between the autonomic and the somatic nervous system?
A= non-conscious, from CNS to motor/smooth muscle, non-myelinated neurones, at least 2 neurones
S=conscious, from CNS to skeletal muscle, myelinated neurones, one neurone connects effector
compare the sympathetic and parasympathetic nervous systems?
S=active during stress, increased HR, pupil dilation and increased VR, neurones secrete noradrenaline
P= active during sleep/relaxation, decreased heart rate, pupil constriction, body can go through digestion, neurones secrete acetylcholine.
why do plants respond to the environment?
-to avoid abiotic stress
-to avoid being eaten by herbivores
what is a tropism?
a directional growth response in which the direction of the response is determined by the direction of the external stimulus.
-eg- phototropism (directional growth towards light), geotropism (directional growth away from gravity)
what is the plant response of nasties?
a mastic response is a non-directional growth response
eg- thigmonasty (plants respond to touch by suddenly dropping their leaves)
what are plant hormones called and why?
phytohormones as they influence growth processes (cell division, cell elongation, cell differentiation)
what effects do the same hormone in plants have ?
-different effects in different tissues
-different effects on the same tissue
what effects do different hormones in plants have?
-opposite effects in the same tissue (ANTAGONISM)
-the same effects on the same tissue (SYNERGISM)
what is the stem?
The main support of the plant
what is the apical bud in a plant?
The growing point of the stem containing meristem tissue consisting of cells that can divide indefinitely
what is the node in the plant?
The part of the stem of a plant from which a leaf, branch or aerial root grows
what is the internode of a plant?
The area of the stem between two adjacent nodes
what is the flower and flower stalk in a plant?
flower-reproductive structure, develops into a fruit
flower stalk-structure that supports the flower
what is a leaf?
broad flat organ adapted for photosynthesis?
what is the lateral bud and lateral shoot?
bud-A growing point along the stem
shoot-brunch that grows from a lateral bud
what is a taproot and lateral root?
tap-The main route, providing water, support and minerals
lateral-A root that grows from the main root
what is the root apex?
The growing point of the root containing meristem tissue consisting of cells that can divide indefinitely
what is the petiole?
a leaf stalk, it attaches the leaf to the plant.
what are the 4 hormones released by plants?
-auxin
-giberrelin
-ethene
-abscisic acid
what are the effects of auxin?
-control cell elongation
-maintain apical dominance
-involved in tropisms
-stimulate the release of ethene
-inhibit leaf/fruit drop
what are the effects of giberrelin?
-promote seed germination
-promote stem elongation
-stimulate pollen tube growth in fertilisation
what are the effects of ethene?
-promotes fruit ripening
-promotes leaf drop and fruit drop (abscission)
what are the effects of abscisic acid?
-maintains dormancy of seeds and buds
-stimulates cold protective responses
-causes stomata to close
what is the definition of a hormone in terms of plant hormones?
a chemical messenger that has a long lasting response and travel to the target cells to produce this response
what are the steps in auxins causing cell elongation?
-auxins produced by meristem cells in the tip
-auxins promote active transport of H+ ions into the plant cell wall
-this lowers the pH, so the low pH is optimum for enzymes, to keep the cell wall flexible
-elastins add enzymes which break bonds within the cell wall
-cell wall is weakened leading to cell elongation and stem growth
what is used to investigate geotropism in plants?
the use of a rotating drum known as a clinostat
what occurs at a clinostat?
the shoot will grow horizontally because the direction of gravity is constantly changing
what do gibberellins affect?
they affect the length of the internodes, which are the regions between the leaves on a stem
what type of plants produce little to no giberrelins?
plants that have short stems
what does having limited giberrelins reduce?
reduces waste and makes the plants less vulnerable to damage by weather and harvesting
what experiment was conducted for gibberellins?
experiment with dwarf and tall pea plants
what do dwarf peas carry?
two copies of a mutant allele of a gene involved in GA synthesis?
-lele
what do tall peas carry?
they carry at least one normal allele of the same gene
-LeLe or Lele
what is the explanation behind applying GA to the stems of dwarf peas which leads to them growing taller?
GA causes growth but dwarf peas cannot make this so it has to be added
what is the explanation behind the idea that GA concentration is higher in tall pea plants compared to dwarf pea plants, which otherwise are genetically identical?
-Le allele codes for an enzyme needed to synthesise GA
-le is mutant so lele dwarf peas can’t synthesise GA
what can you do to make up for deficiencies in pea plant GA synthesis pathways?
two types of dwarf pea plants can be grafted together
-if you graft a second type of dwarf pea into a lele dwarf the graft will grow into a tall pea plant
describe the practical used for gibberellin and seed germination?
-barley seeds (two dead and four alive)
-cut two of the unboiled/alive
-put on starch agar plate containing gibberellin
-repeat with no gibberellin
-incubate both for a day at 25 degrees
-flood each plate with dilute iodine solution after incubation
why are the barley seeds incubated at 25 degrees?
temperature affects enzyme activity, 25 degrees is optimum temperature for germination
what are 3 control variables for the gibberellin experiment?
-age of seeds
-incubation time
-Ga concentration in agar
how does Ga affect seed germination?
-when water is soaked up, Ga is made in the seed embryo and diffuses into endosperm
-this switches on genes in a layer of cells called aleurone which makes amylase
-amylase hydrolyses starch to produce maltose when is then digested to a-glucose, which is used for respiration
-this provides energy as ATP for seedling growth
how does abscisic acid cause stomatal closure?
-when the levels of water fall, ABA is produced in leaf and root cells
-the ABA bind to receptors on the stomata guard cells, causing potassium ions to leave the guard cell
-water follows by osmosis, causing reduced turgor and the guard cells close the stomata
what is phototropism?
plants are sensitive to a lack of light, resulting from a light-sensitive pigment called phytochrome
what does ethene promote in a plant and how?
promotes leaf drop by stimulating production of cellulase
what does cellulase do in a plant?
digests cellulose in the walls of cells in the abscission zone causing petiole to snap, so the leaf falls
what are 3 chemical defences of plants?
-tannins- bitter taste, toxic to insects
-alkaloids-bitter tasting nitrogenous compounds that are poisonous
-terpenoids- acts as toxins to insects and fungi
what is a pheromone in plants?
a chemical made by an organism which affects the social behaviour of other members of the same species
what is the volatile organic compounds in plants?
chemicals that affects behaviour in other species
