Biology by Bradford
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The subtopic in the middle and eleven tasks round it: label four diagrams, complete three tables, put two processes in order and fill 48 gaps. Every standard level statement has a box; the five 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.
Number the steps in order.
When blood glucose falls too low, secrete , which makes liver cells break glycogen down to glucose.
is the removal of waste products of metabolism, such as urea. is control of the osmotic concentration of body fluids, measured in osmol L⁻¹. In the loop of Henle, the ascending limb pumps out by , keeping the osmotic concentration of the medulla high so water can be reabsorbed from the collecting ducts.
Blood pressure forces water and small solutes out of the plasma: . Then all the glucose and amino acids, and most of the water, are , leaving and other unwanted solutes to be excreted in urine.
1234| Type 1 | Type 2 | |
|---|---|---|
| Cause | the immune system destroys the | target cells become to insulin |
| Usual onset | childhood | adulthood |
| Risk factors | inherited genes | , inactivity, family history |
| Treatment or prevention | insulin injections, with blood glucose checks | a healthy diet and , then drugs if needed |
The gland in the neck secretes , which raises the so body cells release more heat. Muscle and adipose tissue are , carrying out the response.
Birds and mammals regulate their temperature by physiological changes and by , such as seeking shade or huddling together.
Homeostasis keeps the within preset limits, whatever happens outside. In humans, body temperature, blood pH, blood glucose concentration and blood are all held near a . feedback brings a variable back whether it rises above or falls below; positive feedback would push it further away.
| Effector | Response when too cold |
|---|---|
| Skin arterioles | : less blood flows near the surface, so less heat is lost |
| Skeletal muscle | : rapid contractions release heat from respiration |
| Brown adipose tissue | : energy from respiration is released as heat instead of being used to make ATP |
| Hair erector muscles | contract, so hairs stand up and trap a layer of insulating |
When too hot, skin arterioles widen, , so more heat is lost from the blood at the surface, and sweat takes heat from the skin as it .
Number the steps in order.
With plenty of water, ADH secretion falls, the aquaporins are taken back into the cells, and a large volume of urine forms.
| Organ | Blood flow in vigorous exercise, compared with rest | Reason |
|---|---|---|
| Skeletal muscles | arterioles widen to bring oxygen and glucose for respiration | |
| Gut | arterioles narrow; digestion can wait | |
| Kidneys | arterioles narrow, sending blood to the muscles | |
| Brain | it must never be short of oxygen |
Homeostasis keeps the internal environment within preset limits, whatever happens outside. In humans, body temperature, blood pH, blood glucose concentration and blood osmotic concentration are all held near a set point. Negative feedback brings a variable back whether it rises above or falls below; positive feedback would push it further away.
When blood glucose falls too low, alpha cells secrete glucagon, which makes liver cells break glycogen down to glucose.
| Type 1 | Type 2 | |
|---|---|---|
| Cause | the immune system destroys the beta cells | target cells become resistant to insulin |
| Usual onset | childhood | adulthood |
| Risk factors | inherited genes | obesity, inactivity, family history |
| Treatment or prevention | insulin injections, with blood glucose checks | a healthy diet and exercise, then drugs if needed |
The gland in the neck secretes thyroxin, which raises the metabolic rate so body cells release more heat. Muscle and adipose tissue are effectors, carrying out the response.
Birds and mammals regulate their temperature by physiological changes and by behaviour, such as seeking shade or huddling together.
| Effector | Response when too cold |
|---|---|
| Skin arterioles | vasoconstriction: less blood flows near the surface, so less heat is lost |
| Skeletal muscle | shivering: rapid contractions release heat from respiration |
| Brown adipose tissue | uncoupled respiration: energy from respiration is released as heat instead of being used to make ATP |
| Hair erector muscles | contract, so hairs stand up and trap a layer of insulating air |
When too hot, skin arterioles widen, vasodilation, so more heat is lost from the blood at the surface, and sweat takes heat from the skin as it evaporates.
Excretion is the removal of waste products of metabolism, such as urea. Osmoregulation is control of the osmotic concentration of body fluids, measured in osmol L⁻¹. In the loop of Henle, the ascending limb pumps sodium ions out by active transport, keeping the osmotic concentration of the medulla high so water can be reabsorbed from the collecting ducts.
Blood pressure forces water and small solutes out of the plasma: ultrafiltration. Then all the glucose and amino acids, and most of the water, are reabsorbed, leaving urea and other unwanted solutes to be excreted in urine.
With plenty of water, ADH secretion falls, the aquaporins are taken back into the cells, and a large volume of dilute urine forms.
| Organ | Blood flow in vigorous exercise, compared with rest | Reason |
|---|---|---|
| Skeletal muscles | increases | arterioles widen to bring oxygen and glucose for respiration |
| Gut | decreases | arterioles narrow; digestion can wait |
| Kidneys | decreases | arterioles narrow, sending blood to the muscles |
| Brain | stays the same | it must never be short of oxygen |