Biology by Bradford
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The subtopic in the middle and 13 tasks round it: label five diagrams, complete three tables, put a process in order and fill 73 gaps. Every standard level statement has a box; the three boxes for higher level only are dashed and badged HL, and drop off for an SL class. Type into the blanks and check them, or print it on A4, Letter or A3 with an answer key.
| Nervous system | Endocrine system | |
|---|---|---|
| Signal | ||
| Carried | along neurons | in the |
| Speed | very fast | |
| Effect lasts | longer | |
| Reaches | particular muscles or glands | any cell with the matching |
Organs are also integrated by the transport of materials and energy: oxygen from the and glucose from the reach every organ by the same route as endocrine signals.
The gland hanging below the brain secretes hormones that control many other glands, and is itself controlled by the region just above it, which links the nervous system to the . The small gland near the centre secretes when it is dark, so levels peak at night: a rhythm that sets the cycle of sleeping and waking.
In a multicellular organism, cells form , which form ; these work together in : a hierarchy of subsystems. Every level needs to carry out its overall function. Integrated, the body has : a cheetah is a deadly predator only because its muscles, eyes, brain, heart and lungs act as one.
Before vigorous activity the secrete epinephrine (adrenaline). It raises heart rate and , widens the , diverts blood to the by dilating their arterioles, and makes the liver break down , so more oxygen and glucose reach the tissues doing the work.
A nerve is a bundle of fibres from two kinds of neuron: neurons carry impulses from receptor cells into the CNS, and neurons carry impulses from the CNS to the , stimulating them to .
The brain combines information from many inputs at once, and it is where and happen. The folded part at the back coordinates skeletal muscle contraction, keeping movements smooth and the body in .
Number the steps in order.
A reflex is : the spinal cord integrates it with no decision by the brain. Choosing to pick up a cup is , started in the .
This phytohormone diffuses into cells freely but cannot diffuse out. When every cell puts the proteins that let it out on the same side, it is moved from cell to cell by and becomes in one part of the plant.
| Phytohormone | Produced in | Transported to |
|---|---|---|
| Auxin | ||
| Cytokinin | ||
| Ethylene | ripening fruit | nearby fruit, as a gas |
The two-way traffic of auxin and cytokinin keeps root and shoot growth . Ripening makes fruit release more ethylene, which speeds ripening: , so all the fruit ripen quickly and together.
Starting to swallow, and egestion of faeces, are , controlled by the . In between, waves of muscle contraction called push food along the gut. They are , coordinated by the in the gut wall.
1234| Heart rate | Ventilation rate | |
|---|---|---|
| Receptors | and chemoreceptors, in the walls of the aorta and | chemoreceptors in the brainstem |
| What they detect | blood ; blood pH, O₂ and CO₂ | a fall in blood pH, as CO₂ forms |
| Signals go to | the heart, changing its rate and stroke volume | the and intercostal muscles |
Both responses are coordinated by the , which sends nerve impulses to the effectors.
Light from one side makes auxin build up on the side of the shoot. There it makes cells secrete into the cell wall, loosening between cellulose molecules, so those cells elongate faster and the shoot bends towards the light: positive . Measuring the angle of curvature with a protractor gives data.
In a multicellular organism, cells form tissues, which form organs; these work together in organ systems: a hierarchy of subsystems. Every level needs coordination to carry out its overall function. Integrated, the body has emergent properties: a cheetah is a deadly predator only because its muscles, eyes, brain, heart and lungs act as one.
| Nervous system | Endocrine system | |
|---|---|---|
| Signal | nerve impulses | hormones |
| Carried | along neurons | in the blood |
| Speed | very fast | slower |
| Effect lasts | a short time | longer |
| Reaches | particular muscles or glands | any cell with the matching receptor |
Organs are also integrated by the transport of materials and energy: oxygen from the lungs and glucose from the small intestine reach every organ by the same route as endocrine signals.
The brain combines information from many inputs at once, and it is where learning and memory happen. The folded part at the back coordinates skeletal muscle contraction, keeping movements smooth and the body in balance.
A reflex is involuntary: the spinal cord integrates it with no decision by the brain. Choosing to pick up a cup is conscious, started in the cerebral hemispheres.
A nerve is a bundle of fibres from two kinds of neuron: sensory neurons carry impulses from receptor cells into the CNS, and motor neurons carry impulses from the CNS to the muscles, stimulating them to contract.
The gland hanging below the brain secretes hormones that control many other glands, and is itself controlled by the region just above it, which links the nervous system to the endocrine system. The small gland near the centre secretes melatonin when it is dark, so levels peak at night: a circadian rhythm that sets the cycle of sleeping and waking.
Before vigorous activity the adrenal glands secrete epinephrine (adrenaline). It raises heart rate and stroke volume, widens the bronchioles, diverts blood to the skeletal muscles by dilating their arterioles, and makes the liver break down glycogen, so more oxygen and glucose reach the tissues doing the work.
| Heart rate | Ventilation rate | |
|---|---|---|
| Receptors | baroreceptors and chemoreceptors, in the walls of the aorta and carotid arteries | chemoreceptors in the brainstem |
| What they detect | blood pressure; blood pH, O₂ and CO₂ | a fall in blood pH, as CO₂ forms carbonic acid |
| Signals go to | the heart, changing its rate and stroke volume | the diaphragm and intercostal muscles |
Both responses are coordinated by the medulla, which sends nerve impulses to the effectors.
Starting to swallow, and egestion of faeces, are voluntary, controlled by the CNS. In between, waves of muscle contraction called peristalsis push food along the gut. They are involuntary, coordinated by the enteric nervous system in the gut wall.
Light from one side makes auxin build up on the shaded side of the shoot. There it makes cells secrete hydrogen ions into the cell wall, loosening cross links between cellulose molecules, so those cells elongate faster and the shoot bends towards the light: positive phototropism. Measuring the angle of curvature with a protractor gives quantitative data.
This phytohormone diffuses into cells freely but cannot diffuse out. When every cell puts the proteins that let it out on the same side, it is moved from cell to cell by active transport and becomes concentrated in one part of the plant.
| Phytohormone | Produced in | Transported to |
|---|---|---|
| Auxin | shoot tips | roots |
| Cytokinin | root tips | shoots |
| Ethylene | ripening fruit | nearby fruit, as a gas |
The two-way traffic of auxin and cytokinin keeps root and shoot growth integrated. Ripening makes fruit release more ethylene, which speeds ripening: positive feedback, so all the fruit ripen quickly and together.