Plant and animal response

In what three ways may plants respond to changes in daylight hours ?

breaking the dormancy of the lateral leaf buds , so they open up and grow new leaves timing the flowering in a plant preparation of tuber formation leaf abscission , causing leaves to fall

How do plants respond to a decrease in temperature ?

Producing sugars , polysaccharides and proteins which act as antifreeze . Supressing or activating different genes at sustained low temperatures .

How do plants respond to a lack of water ?

They close their stomata to prevent water loss by transpiration .

What is herbivory ?

When plants are eaten by a herbivore .

What are the three chemical defences to herbivory ?

Tannins , alkaloids , pheromones .

What are tannins ?

Chemicals that have a bitter taste which puts animals off eating the leaves they are toxic to insects as they inactivate their digestive enzymes .

What are alkaloids ?

Bitter tasting nitrogenous compounds that affect the metabolism of animals ( often protein synthesis is inhibited ) .

What are pheromones ?

Chemicals that affect the behaviour and physiology of another organism .

Which plant folds in respond to touch ?

Mimosa pudica

What is the name for movement in response to touch ?

Thigmonastic movement

How does the mimosa plant bring about the response to touch ?

By movement of potassium ions into / out of specific cells and then movement of water by osmosis into / out of cells , causing a change of shape of the cells .

What is a tropism ?

The directional growth of part of a plant in response to an external stimulus .

What is the name for a tropism in response to light ?

Phototropism

What is the name for a tropism in response to gravity ?

Geotropism

Which two types of tropisms would shoots perform ?

Positive phototropism Negative geotropism

What is apical dominance ?

When the growth of the main central stem ( the apex of the plant ) inhibits the growth of the lateral shoots / branches .

Which hormone causes apical dominance ?

Auxin

Give one example of experimental evidence that shows that auxin causes apical dominance .

If the apical bud / apex is pruned , the lateral shoots / branches begin to grow .

Which hormone causes stem elongation ?

Gibberellins

How is stem elongation caused ?

The individual cells elongate and cell division means there are also more cells .

Give one example of experimental evidence that shows that gibberellins cause stem elongation .

When gibberellins are applied artificially to dwarf plants , they can stimulate stem elongation , even in genetically determined dwarfism .

Which hormones causes seed germination ?

Gibberellins

How do hormones cause seed germination ?

Gibberellins stimulate the production of amylase and protease that break down the food stores found in the seed . The embryo plant uses these food stores to produce ATP for building materials so it can grow and break out of the seed coat .

Give one example of experimental evidence that shows that gibberellins cause seed germination .

Mutant varieties of seeds which do not have the gene to allow the production of gibberellins , do not germinate . However if gibberellins are applied to these seeds externally , they will germinate normally .

Which hormone causes stomatal closure ?

Abscisic acid ( ABA )

How stomatal closure caused ?

The abscisic acid activates changes in the ionic concentration of the guard cells , increasing the water potential , so water moves out of the cells and they become flaccid . This causes the guard cells to close .

Which hormone causes leaf abscission ?

Ethene

How is leaf abscission caused ?

Ethene increases the production of cellulase , which hydrolyses cellulose at the abscission zone and separates the leaf from the stem .

Which hormone is used to control fruit ripening ?

Ethene

How are hormones used in fruit ripening ?

1. Fruit are picked unripe , transported and then exposed to ethene to ripen them ready to be sold . 2. Fruit it exposed to ethene on the plant to ensure they all ripen at the same time .

Which hormone can be used to prevent fruit from dropping ?

Auxin ( or gibberellin for citrus fruit )

Which hormones can be used to encourage fruit to drop ?

Ethene

Which hormone can be used as a rooting powder ?

Auxin

What does a rooting powder and when is it used ?

It encourages the growth of roots and is used during artificially cloning e.g. when taking cuttings .

What is a herbicide ?

A substance that kills plants .

Which hormone can be used as a weed killer ?

Auxin ( synthetic )

Which hormone is used to encourage flowering plants to grow multiple lateral shoots and therefore produce more flowers ?

Ethene

Which hormone used to encourage fruit growth ?

Gibberellins

What are the two main branches of the nervous system ?

Central nervous system Peripheral nervous system

What are the two parts of the central nervous system ?

Brain and spinal cord

Which type of neurone is found in the central nervous system ?

Intermediate / relay neurones

Which types of neurone are found in the peripheral nervous system ?

Sensory and motor neurones

What are the two branches of the peripheral nervous system ?

Somatic and autonomic

What does the somatic nervous system control ?

Conscious activities

What does the autonomic nervous system control ?

Unconscious activities

What are the two branches of the autonomic nervous system ?

Sympathetic and parasympathetic

Which specific branch of the nervous system is involved in fight or flight ' responses ?

Sympathetic

Which specific branch of the nervous system is involved in ' rest or digest ' responses ?

Parasympathetic

Which neurotransmitter is used in the sympathetic nervous system ?

Noradrenaline

Which neurotransmitter is used in the parasympathetic nervous system ?

Acetylcholine

List 5 physiological reactions that are under sympathetic control .

Heart rate increases Pupils dilate Bronchi dilate Digestive activity is inhibited Glycogen converted to glucose in the liver Adrenaline released Peristalsis inhibited

List 5 physiological reactions that are under parasympathetic control .

Heart rate decreases Pupils constrict Bronchi constrict Digestive activity is stimulated Glucose is converted to glycogen in the liver Adrenaline release inhibited Peristalsis stimulated

What is a reflex action ?

Where the body responds to a ( often dangerous or threatening ) stimulus without making a conscious decision .

What are 3 key features of reflex actions ?

1. Automatic 2. Rapid 3. Innate ( not learnt )

Why are reflex actions quicker than other actions ?

They only involve 3 neurones , other actions travel through more neurones . They travel to the closest part of the CNS and back again - this is either the spinal cord or the unconscious part of the brain .

What is the function of reflex actions ?

To prevent injury / damage to the body .

List , in order , the 7 stages to a reflex arc pathway .

Stimulus ->Receptor → Sensory neurone → Intermediate / relay neurone → Motor neurone → Effector -> Response

In the blink reflex , what is the stimulus ?

An object moving towards / touching the eye or wind blow into the eye .

the blink reflex , where are the receptors ?

In the cornea of the eye

In the blink reflex , where are the intermediate neurones located ?

In the pons of the brain , in the central nervous system .

In the blink reflex , what response is caused ?

Muscles connected to the eyelids contract to close the eyelids .

In the knee jerk reflex , what is the stimulus ?

The quadriceps muscle is stretched due to an object hitting the muscle .

In the knee jerk reflex , where are the receptors ?

In the quadriceps muscle .

In the knee jerk reflex , where are the intermediate neurones located ?

The spinal cord

In the knee jerk reflex , what response is caused ?

The quadriceps muscle contracts and the lower leg moves forwards .

Name the six main parts of the brain .

- Cerebrum / cerebral cortex - Cerebellum - Corpus callosum - Medulla oblongata - Pituitary gland - Hypothalamus

Which part of the brain coordinates the autonomic control of heart rate ?

Medulla oblongata

Which part of the brain coordinates clapping of the hands ?

Cerebrum

Which part of the brain coordinates osmoregulation by the kidney ?

Hypothalamus

Which part of the brain coordinates balance when riding a bike ?

Cerebellum

Which part of the brain coordinates the muscles involved in an adult walking ?

Cerebrum

Which part of the brain coordinates the reflex of vomiting ?

Medulla oblongata

Which part of the brain coordinates the muscles required to deliberately bend the elbow ?

Cerebrum

Which part of the brain coordinates speech ?

Cerebrum

Which part of the brain coordinates thermoregulation ?

Hypothalamus

Which part of the brain coordinates posture ?

Cerebellum

Which part of the brain releases hormones ?

Pituitary gland

What is fight or flight ?

An instinct that all mammals possess . It is intended to help mammals to survive by preparing the body to either run / escape or fight for their life .

Which two organ systems coordinate the fight or flight responses ?

The endocrine and nervous systems

Which part of the brain receives information about the threat in the environment ?

The cerebrum

Which part of the brain is stimulated by the cerebrum to then coordinate the response ?

The hypothalamus

Which branch of the nervous system is stimulated by the hypothalamus ?

The sympathetic nervous system

What affect does the sympathetic nervous system have on the adrenal glands ?

Causes it to release adrenaline ( a hormone ) and noradrenaline ( a neurotransmitter ) form the adrenal medulla .

Which hormone is released as a result of corticotropin - releasing hormone ( CRH ) and adrenocorticotropic hormone ( ACTH ) being released from the brain ?

Cortisol

Which hormone is released as a result of thyrotropin- releasing hormone ( TRH ) and thyroid - stimulating hormone ( TSH ) being released for the brain ?

Thyroxine

What is the role of cortisol ?

It leads to the breakdown of glycogen to glucose so there is more glucose for respiration .

What is the role of thyroxine ?

It increases cell metabolism and increases the cells ' sensitivity to adrenaline .

Which fight or flight responses are linked to cardiac muscle ?

Heart beats faster Heart beats more forcefully

Which fight or flight responses are linked to voluntary ( skeletal ) muscle ?

. Breathing is faster . Greater blood flow to the skeletal muscles . Muscles are primed for action e.g. leg muscles to run away

Which fight or flight responses are linked to involuntary ( smooth ) muscle ?

. Increased blood pressure . Less blood flow to the gut and skin . Skin becomes pale Peristalsis slows down . Airways widen . Pupils dilate

The heart is myogenic , what does this mean ?

It has electrical impulses that originate in the muscle .

Which part of the heart is known as the pacemaker ?

The SAN ( sino - atrial node )

Which two organ systems affect the heart rate ?

Endocrine and nervous systems

Which specific part of the brain affects the heart rate ?

The cardiovascular centre in the medulla oblongata .

Where are the receptors that detect changes in the blood and from which information is to the brain ?

The aorta and carotid artery

What do baroreceptors / stretch receptors detect ?

Changes in blood pressure

What do chemoreceptors detect ?

Changes in pH in the blood ( concentration of carbon . dioxide )

Which nerve is used to send an impulse from the medulla oblongata to the SAN to decrease the heart rate ?

The vagus / parasympathetic nerve

Which nerve is used to send an impulse from the medulla oblongata to the SAN to increase the heart rate ?

The accelerator / sympathetic nerve

What 3 effects does adrenaline have on the functioning of the heart ?

. Increased heart rate • Increased stroke volume . • Increased cardiac output