Homeostasis and Response

Many human actions are reflexes. Which statement describes a reflex action?

Figure 3 shows the nerve pathway for a reflex action. The arrows show the direction of the nerve impulse. Which part of the nerve pathway is labelled A?

Which part of the nerve pathway is labelled B?

Which part of the nerve pathway is labelled C?

Which two human actions are reflexes?

Students investigated their reaction times using a computer program. Table 1 shows the results. Calculate mean value X in Table 1.

There is an anomalous result for student R. Identify the anomalous result in Table 1.

Give two factors that might affect a person's reaction time.

A plant shoot responds to the stimulus of light shining on it from one side. What name is given to the type of response shown by the plant shoot?

A student investigated the effect of one-sided light on the growth of plant seedlings as shown in Figure 5. Which diagram shows what the seedling in Experiment 1 would look like after 12 hours?

Which diagram shows what the seedling in Experiment 2 would look like after 12 hours?

Why did the student set up experiment 2 in this investigation?

The student wanted to make the investigation of the effect of one-sided light more valid. The student decided to set up a third experiment. How should the student set up the third experiment?

What is a suitable control variable for the investigation?

Give one stimulus a plant root responds to. Do not refer to light in your answer.

In the human female, an egg is released from one of the ovaries about once every four weeks. During the four weeks, the lining of the uterus thickens and then breaks down. This is called the menstrual cycle. Which two hormones are female reproductive hormones?

Follicle stimulating hormone (FSH) is another female reproductive hormone. What is the function of FSH in the menstrual cycle?

Sperm cells can survive inside a woman's reproductive organs for five days. An egg cell can survive for one day after ovulation. In one woman ovulation occurred on day 14. Give the range of days on which sexual intercourse could result in fertilisation.

If a man and a woman have sexual intercourse and do not want to produce a baby, they may use contraception. Explain how different methods of contraception prevent pregnancy.

The echidna is a mammal that lives in Australia. Figure 9 shows how the body temperature of the echidna varies during the cold winter months. Give the lowest and highest body temperatures for the echidna shown in Figure 9.

In the cold winter months, the echidna hibernates. Figure 9 shows that the echidna woke up from hibernation several times. The echidna's body temperature increased to over 30 °C each time the echidna woke up. How many times did the echidna wake up?

Each time the echidna wakes up, it hunts for food. Suggest why the echidna needs to eat food several times during hibernation.

During hibernation: - the echidna sleeps - the echidna's body temperature decreases to below 5 °C - the echidna uses food stored in its body cells to provide energy. What process releases energy from stored food?

Most mammals use a lot of energy to evaporate sweat. The echidna does not sweat. Suggest one use of energy in the echidna's body.

The control of body temperature is important in the human body. An athlete trained in a hot climate. On one day, the athlete lost 3200 cm³ of water in sweat. Evaporation of 1 cm³ of sweat requires 2.5 kJ of energy. Calculate the energy the athlete used for evaporation of sweat.

On a different day the athlete used 6000 kJ of energy to evaporate sweat. The athlete's energy intake was 24 000 kJ. Calculate the percentage of the athlete's energy intake used for evaporation of sweat.

Some days the athlete did not do any training and rested at home. What effect would resting have on the volume of sweat produced each day?

What are two reasons for surrounding the seedlings with damp blotting paper? Choose two options.

Apparatus B is a control. Explain why apparatus B is needed.

Auxin is a plant hormone. Explain how auxin causes the results in apparatus A.

Farmers can use plant hormones to control the growth of plants. Give two uses of auxin.

A farmer sprayed an apple tree with gibberellin. Suggest two reasons why the farmer sprayed the apple tree with gibberellin.

Student B's reaction is coordinated by the nervous system. Give two ways that coordination by the endocrine system is different from coordination by the nervous system.

The adrenal gland produces the hormone adrenaline. Describe two effects of adrenaline on the human body.

Hormones can be used for controlling human reproduction. Explain the use of hormones in: - contraception - the treatment of infertility.

Conditions inside and outside of the human body often change. Homeostasis helps the human body to survive changing conditions. Explain what is meant by the term 'homeostasis'.

The kidneys have an important role in homeostasis. Describe what happens to glucose, protein and urea in the kidneys.

Explain how ADH affects the production and concentration of urine by the kidneys.