The State of blood capillaries

Study the diagrams below and answer the auestinne 3.1.1 a) Which skin (A or B) will have a higher temperature? b) Give a reason for your answer in question 3.1.1. a). c) Give the term to describe the state of blood capillaries in B. 3.1.2 Give ONE reason why the body temperature of a person has to be kept constant. 3.1.3 An athlete is running$$1500\mathrm{m}$$during a competition at 13:00.

Describe another homeostatic mechanism in the skin that will counteract the increase in his body temperature. 2 One characteristic of all living organisms is that they are irritable. They can sense changes in the environment, interpret the changes and react accordingly.

3.2.1 Name the part in the human body that a) senses changes in the environment. b) conducts the message to the central nervous system. 3.2.2 Draw a labeled diagram of the neuron that conducts impulses from the central nervous system to the effectors. Indicate the direction of an impulse in the neuron by using an arrow.

3.3 The diagram below represents a phase during meiosis in a female human body. Only four pairs of the chromosomes are represented in the diagram namely pairs$$18,19,20$$and$$21.$$3.3.1 Give the term for each of the following descriptions: a) The meiotic process in a female during which an ovum is produced. b) A pair of chromosomes such as number$$18.$$3.3.2 Identify the phase visible in the diagram. 3.3.3 Motivate your answer in question 3.3.2. 3.2.4 Give the term used to describe the abnormal process that occurs at chromosome pair 21 in this diagram.

3.3.5 How many chromosomes will each of the four gametes have after this meiotic division process? 3.3.6 a) If an ovum with an extra chromosome of this kind mentioned in question$$\mathrm{3.3.5}$$is fertilized by a normal sperm it can lead to a certain type of trisomy.

Give the name of the defect this type of trisomy causes in humans. b) Name THREE distinct features of a person with the disorder mentioned in question