2 (cells + control) exam qs

• Which structure of the eye contains the light receptor cells?

  Retina
• The optic nerve transfers electrical signals from the eye to the central nervous system. The optic nerve is a what neurone?

  Sensory neuron
• Name the region of the central nervous system responsible for vision:


  Cerebrum
• Macular degeneration is a defect of the eye that occurs when some cells of the retina begin to break down. Embryonic stem cell therapy has been used to improve the vision of some patients with macular degeneration. Explain how embryonic stem cells could be used to treat macular degeneration:

  The embryonic stem cells can be stimulated to producing cells of the retina that can be transplanted into a patient's eye to replace the damaged cells
• A scientist wanted to test if prolonged use of a computer affected reaction time. The scientist tested the reaction times of 10 people under the same environmental conditions. These people then used a computer for three hours. The scientist tested their reaction time again. Give three ways that the scientist could improve this method to determine if prolonged use of a computer affects reaction time.


  Vary the time for computer usage, make the activity on the computer each person does the same, repeat the test using more people, repeat the test at different times of the day
• What is structure A and B?

  A is a dendrite, B is the nucleus

  
• The axon carries information across the neurone as...

  Electrical impulses
• Describe the role of the myelin sheath surrounding the axon:

  It insulates the electrical impulse and allows quicker conductance
• Humans have reflexes. Describe the route of an impulse through a reflex arc:

  A stimulus is detected by a receptor and the sensory neurone will pass the impulse to the relay neurone in the spinal cord which then passes the impulse onto the motor neurone that then passes the impulse to the effector (muscle or gland) which initiates a response
• Describe how the structure of a red blood cell is related to its function:

  It is a biconcave disk which means it has a large surface area increasing oxygen uptake. It has a thin membrane meaning there is a short distance for diffusion. It contains haemoglobin to bind oxygen. It is flexible and small to get through capillaries.
• Describe the function of platelets:

  They stop bleeding and prevent infection (by sealing a wound forming a scab and preventing entry of microbes)
• Compare mitosis and meiosis:

  In mitosis, genetically identical cells are produced, it occurs in the formation of body cells for growth + repair and there is one division. In meiosis, non-identical cells are produced, it occurs in the formation of gametes for sexual reproduction resulting in genetic variation and there are 2 divisions.
• After fertilisation, mitosis takes place to form an embryo, the embryo develops into new coral. Describe mitosis:

  Cell divides producing 2 diploid cells that are genetically identical
• After fertilisation, mitosis takes place to form an embryo, the embryo develops into new coral. Describe how the embryo develops into new coral:

  There are many cell divisions that become bigger and become specific cells - new coral
• Explain how active transport and diffusion provide a plant with named substances it needs for growth?

  Active transport moves mineral ions from the soil into root hair cells from a low concentration to a high concentration. Diffusion is a passive process and gases diffuse from a high to low concentration. Gas exchange in a leaf occurs by diffusion allowing carbon dioxide in for photosynthesis and diffusing oxygen out for respiration.
• Structure X on the diagram contains DNA. What is structure X?

  Nucleus

  
• Define fertilisation:

  Sperm fuses with egg and their genetic information combines. The fussed cell is then diploid and a zygote is formed.
• Describe the function of mitochondria:

  They are the site of aerobic respiration as energy is released for movement
• Explain how type 1 diabetes can be controlled:

  Have a low carbohydrate diet, increase exercise, inject insulin to regulate glucose levels
• Explain how impulses are transmitted in a reflex arc to prevent a person from injuring themselves:

  A reflex response is an involuntary response that involves sensory, relay and motor neurones. The relay neurones are in the spinal cord. Impulses travel along neurones as electrical signals and at the junction between 2 neurones, there is a synapse. The message is carried across the synapse by neurotransmitters and the message travels along the axon and dendron of the sensory neurone to the spinal cord.
• What is Neurone A?

  Motor neurone

  
• Where does neurone B send information?

  Brain and spinal cord

  
• How does information travel along the axon of a sensory neurone?

  As an electrical impulse from receptor cells to the brain or spinal cord or another neurone