Plant and animal responses Flashcards
Fill in the blanks about the ‘fight or flight’ response (8) :
A threat is detected by the ___ nervous system. The h___ activates the sympathetic nervous system and the adrenal-cortical system.
The sympathetic nervous system sends ___ to glands and smooth muscles. It also activates the adrenal ___, causing it to release the stress hormones ___ and ___.
The adrenal-cortical system secretes hormones into the ___. The ___ gland then is stimulated by the hypothalamus to release ACTH, that cause the adrenal cortex to release many hormones.
- Autonomic (1)
- Hypothalamus (1)
- Impulses (1)
- Medulla (1)
- Adrenaline (1)
- Noradrenaline (1)
- Bloodstream (1)
- Pituitary (1)
Describe three physical responses induced in ‘fight or flight’ and their purposes. (6)
- Heart rate increases (1); pumps more oxygenated blood around the body. (1)
- Pupils dilate (1); to take in as much light as possible. (1)
- Arterioles in skin constrict (1); more blood goes to major muscle groups. (1)
- Blood glucose level increases (1); provides energy for muscle contraction. (1)
- Smooth muscle of airway relaxes (1); allows more oxygen to the lungs. (1)
- Non-essential systems shut down (1); to focus resources on emergency functions. (1)
Describe the action of adrenaline. (5)
- Adrenaline binds to receptors on a liver cell’s cell-surface membrane. (1)
- The enzyme adenylyl cyclase is activated. (1)
- ATP is converted to cyclic AMP (cAMP). (1)
- cAMP acts as a secondary messenger. (1)
- cAMP activates other enzymes which cause glycogenolysis. (1)
What part of the brain is responsible for controlling heart rate? (1)
Medulla oblongata (1)
There are two centres in the medulla oblongata.
What are they linked to the sinoatrial node (SAN) by? (1)
What are the centres responsible for? (2)
- Motor neurones (1)
- One centre increases heart
rate, sending impulses through the sympathetic nervous system. (1) - One centre decreases heart rate, sending impulses through the parasympathetic nervous system. (1)
Explain how chemoreceptors are responsible in controlling heart rate.
- Chemoreceptors are sensitive to change in pH.
- When blood carbon dioxide levels rise and carbonic acid is formed, pH lowers.
- Centre in the medulla oblongata that increases heart rate is stimulated. (1)
- Impulses are sent to the SAN via the sympathetic nervous system. (1)
- SAN increases heart rate. (1)
Explain how chemoreceptors are responsible in controlling heart rate. (4)
- Baroreceptors are sensitive to changes in pressure. (1)
- When blood pressure is too high, the centre in the medulla oblongata that decreases heart rate is stimulated. (1)
- Impulses are sent to the SAN via the parasympathetic nervous system. (1)
- SAN decreases heart rate. (1)
Same marks for the other way round (blood pressure too low).
Summarise the two systems that make up the mammalian nervous system. (2)
Central nervous system (CNS) consists of the brain and spinal cord. (1)
Peripheral nervous system (PNS) consists of the neurones that connect the CNS to the rest of the body (sensory/motor neurones). (1)
What is the difference between the somatic nervous system and the autonomic nervous system? (4)
The somatic nervous system is under conscious control, e.g choosing to lift your arm. (1) Impulses are sent to muscles. (1)
The autonomic nervous system is under subconscious control and is involuntary, e.g causing your heart beat. (1) Impulses are sent to glands and smooth muscles. (1)
The autonomic nervous system is divided further into the sympathetic and parasympathetic nervous systems. What is the difference between the two? (2)
Sympathetic nervous system increases activity (1), parasympathetic nervous system decreases activity. (1)
Describe the functions of the cerebrum, cerebellum, medulla oblongata, hypothalamus and pituitary gland. (5)
- Cerebrum; controls voluntary actions such as memory, conscious thought and learning. (1)
- Cerebellum; controls unconscious functions, such as posture, balance and non-voluntary movement. (1)
- Medulla oblongata; used for autonomic functions, such as controlling heart rate and breathing rate. (1)
- Hypothalamus; regulates temperature and water balance.
- Pituitary gland; stores and secretes hormones that regulate body functions. (1)
Define the term ‘reflex’. (1)
An involuntary response to a sensory stimulus (1)
Fill in the blanks (2):
Ethene is involved in abscission and the ___ of climacteric fruits (partly, by greatly increasing rate of ___).
Ripening (1)
Respiration (1)
Describe how ethene is used commercially in the production of perfectly ripe climacteric fruit. (4)
- Fruit harvested when fully formed, but not ripe. (1)
- Unripe fruit is harder and less easily damaged in transport. (1)
- Each batch of unripe fruit is then exposed to ethene in controlled conditions. (1)
- Ensures each batch ripens at the same rate. (1)
- Each batch is in the same stage when they are put on sale. (1)
What are hormone rooting powders used for? (1)
Propagation - cuttings are dipped into the powder to cause new roots to grow, forming a new plant. (1)
