Paper-2

• What does gibberellin do?


  Stimulates seed germination, stem growth and flowering.
• What does ethene do?

  Stimulates the ripening of fruit.

  
• How can auxins be used to kill weeds?

  Most weeds growing in a field of crops or on a lawn are broad leaved, in contrast to grasses and cereals which are narrow leaves. Selective weedkillers have been developed using auxin to kill only broad leaf plants by disrupting their growth patterns.
• What will happen to a shoot if it is growing sideways?

  Auxin moves to the lower side of the shoot and the root. This is caused by gravity. It cause the lower side of the shoot to grow faster so the shoot bends upwards towards the light. In the root the lower side grows slower meaning the root bends downwards.

  
• What effect does auxin have on shoots and roots?

  Auxin promotes growth in shoots and inhibits growth in roots.
• What will happen if the tip of a shoot is removed from a plant?

  There will be no auxin as auxin is found in the shoot. The plant will not grow.
• If light is coming from one side of a plant what will happen.

  Auxin diffuses to the dark/shaded side of plant. This causes the cells to grow faster on that side (elongate) which causes the shoot to bend twards the light.

  
• What does phototropism mean?

  The movement of a plant towards light.
• What is auxin?

  A growth hormone found in the roots and shoots of plants. It controls the growth of plants in response t light, gravity and water.
• Why are computers a better way of measuring reaction time than the ruler test?

  Computers can give a more precise reaction time because they remove human error.

  Computers can record the reaction time to a millisecond so more accurate.

  Computers remove the possibility that a person can predict when to respond by using a persons body language.
• What is reaction time affected by?

  Age, drugs e.g. caffeine or gender
• What is reaction time?

  The time it takes to respond to a stimulus

  
• Evaluate the benefits and risks of procedures carried out on the brain and the nervous system.

  +ve- Can lead to the treatment for disorders of the nervous system

  -ve- The brain is complex and delicate. The treatment of brain damage is difficult. It also carries risks such as physical damage or increased problems with brain damage e.g. speech.

  NB: ADD A CONCLUSION.See an expert-written answer!We have an expert-written solution to this problem!
• Name some methods by which scientists study the brain.

  MRI, Electrical stimulation, Studying patients with damage to their brain.

  
• What is the pituitary gland ?

  It is the master gland. It produces many hormones that regulate homeostasis e.g ADH, FSH

  
• What is the hypothalamus?

  controls homeostasis and pituitary gland

  
• What is the cerebellum?

  At the back, responsible for muscle contraction & balance

  
• What is the medulla?

  The base, controls unconscious activities like breathing, movement in the intestines and heartbeat

  
• What is the cerebral cortex?

  The outer wrinkly layer of the brain, controls consciousness, memory and language

  
• What is the brain in charge of?

  It is in charge of our complex behaviours, controls and coordinates everything we do breathing, sleeping, memory etc.
• What is the brain made from?

  Millions of interconnected neurones
• Name some of the treatments for vision defects.

  Contact lenses, laser eye surgery and replacement lens surgery.
• What is short sightedness (myopia)? How do you treat it?

  People are unable to focus on FAR objects. This occurs when the lens is the wrong SHAPE and refracts the light too much. The image is brought into focus IN FRONT of the retina. You can use glasses with a concave lens to treat it.

  
• What is long sightedness (hypermyopia)? How is it treated?

  People are unable to focus on near objects. This occurs when the lens doesn't refract the light enough or the eyeball is too short. The image is brought into focus BEHIND the retina. You can use glasses with a convex lens to treat it.

  
• Explain how the eye focuses on something that is far away.

  The ciliary muscles relax which causes the suspensory muscles to pull tight. This causes the lens to become thinner so refracts light by a smaller amount.
• Explain how the eye focuses on something that is near to it.

  The ciliary muscles contract which slacken the suspensory muscles. This causes the lens to become fat (more curved) so increases how much light is bent.
• Define accommodation.

  Where the eye focuses light on the retina by changing the shape of the lens.

  
• Explain the iris reflex in dim light.

  In dim light a reflex is triggered to make the pupil dilate. The CIRCULAR muscles RELAX and the RADIAL muscles CONTRACT.

  
• Explain the iris reflex in very bright light.

  In very bright light a reflex is triggered to make the pupil smaller. The CIRCULAR muscles CONTRACT and the RADIAL muscles RELAX.

  
• Why is the iris reflex needed?

  To prevent light from damaging the retina.
• What is the optic nerve?

  Carries impulses from the receptors on the retina to the brain

  
• What is the ciliary muscles and suspensory ligaments?

  Control the shape of the lens

  
• What is the lens?

  Focuses the light into the retina

  
• What is the retina?

  Contains receptor cells called rods and cones. These are sensitive to colour and light intensity.

  
• What is the iris?

  A muscle that controls the diameter of the pupil and how much light enters. The coloured part of the eye.

  
• What is the pupil?

  The hole in the centre where light enters

  
• What is the cornea?

  Outer transparent layer, bends/refracts light into the eye

  
• What is the sclera?

  The tough supporting wall of the eye

  
• What are the ethical concerns linked to IVF?

  IVF leads to unused embryos which are destroyed or used for medical research. (Potential life).

  Genetic testing could be carried out on the embryo which could lead to designed babies.
• What are the pros and cons of IVF?

  PRO: Gives an infertile couple a child.

  CON: Multiple births, these are risky, more chance of still birth and miscarriage.

  CON: Success rate is low

  CON: Emotionally and physically stressful

  CON: Side effects of hormones e.g. abdominal pain