B5- Homeostasis

Question 1

What is homeostasis?

Answer 1

Maintaining internal body conditions

Question 2

Why is homeostasis important?

Answer 2

To maintain optimum conditions for enzymes and all cell functions

Question 3

List three things controlled by homeostasis?

Answer 3

• > Body Temperature
• > Blood glucose
• > Water levels

Question 4

Name the cells that detect a stimulus (change in the environment)?

Answer 4

Receptors

Question 5

What are two types of effector?

Answer 5

Muscles and glands

Question 6

Put the following in order for a nerve response:

Effector/stimulus/response/coordinator/receptor

Answer 6

Stimulus->receptor->coordinator->effector->response

Question 7

A)What is the name given to the glands that produce hormones?

B)how do these hormones reach their target organ?

Answer 7

A) endocrine system

B) through the blood stream

Question 8

Which part of the body coordinates blood glucose concentration?

Answer 8

Pancreas

Question 9

Name the hormone that reduces blood sugar levels

Answer 9

Insuline

Question 10

Describe how blood glucose is controlled if it gets too high?

Answer 10

• pancreas produces insuline
• insuline causes glucose to move from blood into cells
• in the liver and muscle cells, glucose is converted to glycogen for storage

Question 11

What type of diabetes is inherited?

Answer 11

Type 1

Question 12

Obesity is a risk factor of which type of diabetes?

Answer 12

Type 2 diabetes

Question 13

What would a doctor prescribe someone with type 1 diabetes?

Answer 13

Insuline injections

Question 14

What would a doctor prescribe someone with type 2 diabetes?

Answer 14

• regular exercise

* low carbohydrate diet

Question 15

In which type of diabetes is no insuline produced?

Answer 15

Type 1 diabetes

Question 16

In which type of diabetes is insulin still produced but no longer effective?

Answer 16

Type 2 diabetes

Question 17

Explain how blood glucose concentration is controlled if blood glucose levels are too low.

Answer 17

• pancreas produces glucagon
• glucagon causes liver to convert glycogen back into glucose
• glucose is released back into the blood

Question 18

Explain how glucagon and insulin interact in the negative feedback cycle.

Answer 18

• If blood glucose levels are too high, insulin is produced by the pancreas which removes glucose from the blood into the liver and muscle cells where it is converted to glycogen.
• If blood glucose levels are too low, pancreas releases glucagon, this stimulates the liver to convert glycogen back into glucose. Glucose is released back into the blood.

Question 19

A) what three ways is water lost from the body?

B) what two ways are ions lost from the body?

C) what two ways are urea lost from the body?

Answer 19

A) lungs, sweat and urine

B) sweat and urine

C) sweat and urine

Question 20

Explain the effects that osmotic changes have on cells.

Answer 20

• Osmotic changes cause cells to either gain or lose water

* If they gain or lose too much water they won’t function correctly

Question 21

Describe how the kidneys maintain the water balance inside the body.

Answer 21

• They control the concentration of urine- controlled by ADH
• If water levels are too high, pituitary gland releases less ADH so that less water Is reabsorbed by the kidneys- more dilute urine.
• If water levels are too low, pituitary glad releases more ADH so more water is reabsorbed by the kidneys- more concentrated urine.

Question 22

What’s a problem with losing ions, urea and water through the lungs or skin?

Answer 22

There’s no control over how much is lost

Question 23

Describe how ammonia is produced in the body.

Answer 23

• Protein digestion results in excess amino acids

* In the liver these amino acids are deaminated to form ammonia

Question 24

How and why does the body get rid of ammonia?

Answer 24

• ammonia is immediately converted to urea

* Because ammonia is toxic so our bodies need to get rid of it quickly

Question 25

Describe how the kidneys work.

Answer 25

* Kidneys filter waste products out of the blood through filtration * The right amount of some ions, water and glucose are reabsorbed back into the blood by a process called selective reabsorption. * Kidneys produce urine containing waste products

Question 26

Name three substances reabsorbed back in the kidneys.

Answer 26

* Water * Ions * Glucose

Question 27

Describe how ADH controls the water levels in the blood when blood becomes too concentrated.

Answer 27

* ADH released by pituitary gland | * this causes more water to be reabsorbed back into the blood from kidney tubules

Question 28

Explain why the control of blood water levels by ADH is a negative feedback process.

Answer 28

Higher levels of ADH will lead to the inhibitation of ADH

Question 29

Explain how dialysis works.

Answer 29

* Patient connected to dialysis machine for 3-4 hours. * Patients blood flows through a partially permeable membrane surrounded by dialysis fluid. * Urea, Ions and water diffuse across the membrane into the fluid. * Dialysis fluid contains the same concentration of ions, water and glucose as healthy blood to maintain appropriate concentration gradient between patients blood and dialysis fluid.

Question 30

What are the advantages and disadvantages of treating kidney failure with mechanical device or transplant?

Answer 30

``` Mechanical device: Advantages: -Can keep patient alive until kidney transplant. Disadvantages: -each session takes hours -may cause blood clots -expensive for the NHS ``` ``` transplant: Advantages: -long term solution and only cure Disadvantages: -risk of rejection -long waiting lists ```

Question 31

``` Give the functions of the following parts of the eye: Cornea Iris Lens Ciliary muscles Suspensory ligaments Retina Optical nerve Sclera ```

Answer 31

* Cornea-Transparent front layer that bends light Into the eye. * Iris-Contains muscles that control the shape of the pupil. * Lens-Focus light on the retina. * Ciliary muscle-Control the shape of the lens * Suspensory ligaments-Control the shape of the lens. * Retina-Contains light receptor cells-Where image is formed. * Optical nerve-Carries impulses from retina to the brain. * Sclera-Tough outer layer to protect the eye.

Question 32

Name the sense organ containing receptors sensitive to light intensity and colour.

Answer 32

The eye

Question 33

What does ‘accommodation’ mean in terms of eyesight?

Answer 33

The process of changing the shape of the lens to focus on near or far objects.

Question 34

Describe what happens to the ciliary muscles, suspensory ligaments and lens when focusing on... A)...near objects B)...far objects

Answer 34

A) Near objects: Ciliary muscles contract, suspensory ligaments loosen and lens becomes thicker and refracts light strongly. B) Distant objects: Ciliary muscles relax, suspensory ligaments tighten and lens becomes thinner and light is refracted slightly.

Question 35

Give the name for the following eyesight conditions: A) Short sightedness B) Long sightedness

Answer 35

A) myopia B) hyperopia

Question 36

Give three ways in which short and long sightedness are treated.

Answer 36

* Spectacles or contact lenses that refract light to focus on the retina * Laser eye surgery- changes shape of cornea * Replacement eye lens

Question 37

A) What’s the name of the eye condition that means light rays meet before hitting the retina? B) How would you Correct this?

Answer 37

A) Myopia B) wear glasses with concave lenses

Question 38

A) What’s the name of the eye condition that means light rays would meet beyond the retina? B) How would you correct this?

Answer 38

A) Hyperopia B) Wear glasses with convex lenses

Question 39

Name the plant hormone responsible for initiating seed germination.

Answer 39

Gibberellins

Question 40

A) What is the plant response to light called? B) What is the plant response to gravity called?

Answer 40

A) Phototropism B) Geotropism

Question 41

Name the plant hormone that coordinates and controls growth in plants.

Answer 41

Auxins

Question 42

Explain how auxins control the growth of a shoot toward light.

Answer 42

* Auxins collect on the shaded side. * Unequal distribution of auxins... * ...Causes unequal growth rates. * Growth stimulated on shady side. * shoot will bend towards the light.

Question 43

What effect do auxins have on... A)...Shoots B)...Roots

Answer 43

A) Stimulates growth B) Inhibits growth

Question 44

Name the hormone that controls cell division in and fruit ripening in plants.

Answer 44

Ethene

Question 45

What three things can auxins be used for in agriculture?

Answer 45

* weed killers * rooting powder * promoting growth in tissue culture

Question 46

What three things can gibberellins be used for?

Answer 46

* End seed dormancy/initiate germination * Promote flowering * Increase fruit size

Question 47

How does the eye change for... A)...Very bright light? B)...Dim light?

Answer 47

A) Circular muscles in the iris contract and the radial muscles relax. This causes the pupil to become smaller and reduce the amount of light that enters the eye. B) Circular muscles relax and the radial muscles contract. This makes the pupil wider and increases the amount of light that enters the eye.