exam questions

Question 1

How are equines water levels monitored

Answer 1

water levels are monitored by special neurones/ osmoreceptors; the negative feedback mechanism returns water levels back to a set point

Question 2

What happens when equines water levels are too low

Answer 2

• Increased thirst meaning increased water intake
• antidiuretic (ADH) hormone is secreted from the hypothalamus and stored in pituitary gland - released when dehydrated
• Action of ADH causes more water to be reabsorbed

Question 3

What happens when equines water levels are too high

Answer 3

• Reduced thirst, results in decreased water intake

- ADH not secreted so water is not reabsorbed in kidney meaning, urine is dilute and in larger volumes.

Question 4

Equines in the wild are sometimes in danger of attack from predators. Explain 2 ways in which the equines orbit position affects its field of vision

Answer 4

• The orbit position causes a blind spot to the rear and straight ahead at short distance.
• Results in monocular vision to the side. this allows a greater field of vision.

Question 5

when an equine sees a predator approaching, the sympathetic nervous system responds in different ways

Answer 5

Fight or Flight

Question 6

Sympathetic nervous system causes the production of epinephrine. what effect does this have on the blood glucose levels

Answer 6

Blood glucose level is increased so that tissues are able to gain energy

Question 7

3 other responses of the sympathetic nervous system when an equine sees a predator approaching.

Answer 7

• increased heart rate so that blood can transport substances around the body quicker.
• increased muscle strength so that strides are more powerful.
• reduced digestive process, to focus on body functions needed for immediate survival

Question 8

2 physical signs of a mare being in heat

Answer 8

• repeated urination/ mucus squirting
• elevation of tail
• “winking” opening/closing of the vulva

Question 9

part of a breeding programme, a mare was given hormone implants that act in a similar way to luteinizing hormone (LH). How does the hormone implant affect the oestrous cycle of a mare

Answer 9

• ovulation may be caused because peak in LH is the trigger for ovulation.
• LH causes follicles to mature/rise in oestrogen levels.

Question 10

Horses are polyoestrous, or seasonal breeders. How does a mares oestrous cycle change in winter months

Answer 10

Day lengths are short during winter, the pineal gland detects day length. the pineal gland secretes more melatonin. mares are anoestrus in winter

Question 11

An equine moves and responds in different ways as biological demands change, such as when they need to move faster

Answer 11

• Muscles work in antagonistic pairs to bring about movements at joints.
• cells and tissues require oxygen and nutrients to respire and produce energy for biological activities.
  INCREASED GAIT SPEEDS:
• larger force when hooves strike the ground
• Stride length and frequency