B1.2 Nerves and hormones

Question 1

What does the nervous system enable humans to do?

Answer 1

It enables them to REACT to their surroundings and COORDINATE their behaviour

Question 2

Which cells detect stimuli (changes in the environment)?

Answer 2

Cells called receptors

Question 3

Where are the 5 places with receptor cells and what do they detect?

Answer 3

• EYES, sensitive to LIGHT
• EARS, sensitive to SOUND and CHANGES IN POSITION (balance)
• TONGUE and NOSE, sensitive to chemicals, enable us to taste and smell
• SKIN, sensitive to TOUCH, PRESSURE, PAIN and to TEMP changes

Question 4

What are three organelles in the light receptor cells?

Answer 4

(Similarly to most animal cells)

Nucleus, cytoplasm, cell membrane

Question 5

Reflex actions are automatic and rapid. What are the three neurons involved?

Answer 5

Sensory, relay and motor

Question 6

The path of a reflex action is…

5

Answer 6

RECEPTOR –> SENSORY –> CNS, relay –> MOTOR –> EFFECTOR

Question 7

What is an effector and what does it do? (4)

Answer 7

Muscle, responds by contracting

Gland, responds by secreting chemical substances

Question 8

What are the four internally controlled conditions inside of the body?

Answer 8

• Water content
• Ion content
• Blood sugar levels
• Temperature

Question 9

How is water and ion content controlled inside the body? (different way for each)

Answer 9

• Water= sweating, exhalation, sweating urine

- Ions= sweating, urine

Question 10

Why are blood sugar levels and temperature controlled?

Answer 10

• Temp= for enzymes

- Sugar= to provide cells with constant energy

Question 11

What do hormones do? (2)

Answer 11

• REGULATE the many functions of organ and cells

- COORDINATE many processes within the body

Question 12

Name the three hormones involved in the menstrual cycle and their functions

Answer 12

• FSH, matures eggs
• LH, stimulates the release of eggs
• Oestrogen, inhibits the further production of FSH

Question 13

What do oral contraceptives contain and why?

Answer 13

• Oestrogen and progesterone

- to inhibit egg maturation

Question 14

What did the first birth-control pills contain and why was this a problem?

Answer 14

• Large amounts of oestrogen

- Significant side effects; changes in weight, mood and blood pressure

Question 15

What do birth-control pills now contain?

Answer 15

Less oestrogen or progesterone only (for less side-effect)

Question 16

When and why would a woman be given FSH and LH?

Answer 16

• In Vitro Fertilisation (IVF)

- To stimulate the maturation of several eggs

Question 17

What happens during IVF? (4)

Answer 17

• Eggs COLLECTED
• FERTILISED by sperm
• DEVELOP into embryos
• When they’re tiny balls of cells, 1 or 2 embryos are INSERTED into the mother’s uterus

Question 18

In what directions do plants grow? Include gravity in your answer.

Answer 18

• Shoots: towards light, against force of gravity

- Roots: towards moisture in the earth, in direction of the force of gravity.

Question 19

What three things are plants sensitive to?

Answer 19

• Light
• Moisture
• Gravity

Question 20

What does auxin control?

Answer 20

Phototropism

Geotropism

Question 21

Why do plants have unequal growth rates?

Answer 21

• Unequal distribution of hormones

- Which alters the responses of plant roots and shoots to light, gravity and moisture

Question 22

What are plant growth hormones used for in agriculture?

Answer 22

• Weed killers

- Rooting hormones.

Question 23

From which organs is water lost in the body? (3)

Answer 23

• Lungs
• Skin
• Kidneys