mechanisms to maintain internal enviro

Question 1

define endotherms

Answer 1

Endotherms: organisms that can maintain a constant internal body temperature within a very narrow range of tolerance limits despite variations in the ambient temperature

Question 2

define adaptation

Answer 2

Adaptation: characteristic that an organism posses that will increase its survival and reproductive chances

Question 3

TRENDS AND PATTERNS

examples of BEHVIOURAL ADAPTATIONS

Answer 3

• Movement: move to shaded/exposed areas to decrease/increase heat exposure
  
  • Migration: move to different habitats that are within their tolerance range
  • Sunbaking: increasing surface area available for heat absorption
  • Licking: enabling more heat to be evaporated through saliva
  • Drinking water: to replenish fluids to maintain cells in a consistent isotonic state
  • Nocturnal activity: remain inactive during the heat of the day to refrain from activity that increases metabolic body heat

Question 4

examples of STRUCTURAL ADAPTATIONS

Answer 4

• Insulation: feathers, hair and fur trap a layer of air next to the skin which reduces amount of heat lost
  
  • Surface area to volume ratio: more compact bodies reduce surface area available for heat exchange, allowing animals to retail heat more effectively

Question 5

examples of PHYSIOLOGICAL ADAPTATIONS

Answer 5

• Vasoconstriction and vasodilation: allow animals to regulate blood flow to increase or decrease the amount of heat lost to surroundings
  
  • Metabolic activity: can be increased to increase the production of heat energy internally, or decreased to cool the body temperature
  • Muscle contraction: making small movements produces heat energy
  • Sweating: allows sweats to evaporate from the skin, which has a cooling effect

Question 6

INTERNAL COORDINATION SYSTEMS THAT MAINTAIN HOMEOSTASIS
- endocrine and nervous systems work together

define HORMONES

Answer 6

• Are chemical signalling molecules, transported by the bloodstream, used by the body to regulate physiology and behaviour

Question 7

where are hormones produced are how are they transported?

Answer 7

○ Produces in the glands and transported around the body using the circulatory or lymph systems

Question 8

what is the process that hormones cause cells to change their activity to maintain homeostasis

Answer 8

○ Binds to specific receptors on their surfaces, enacting changes in a process called signal transduction

Question 9

EXAMPLES OF HORMONES

what hormone and its function is produced in the PINEAL GLAND

Answer 9

melatonin- affects reproductive development and daily physiologic cycles

Question 10

EXAMPLES OF HORMONES

what 3 hormone and its function is produced in the PITUATARY GLAND

Answer 10

growth hormone- controls bone and muscle growth
antidireutic hormone- increases reabsorption of water in kidneys
gonadotrophins- controls development of ovaries and testes

Question 11

EXAMPLES OF HORMONES

what hormone and its function is produced in the THYROID GLAND

Answer 11

thyroxin- controls rate of metabolism and rate that glucose is used up in respiration and promotes growth

Question 12

EXAMPLES OF HORMONES

what hormone and its function is produced in the ADRENAL GLAND

Answer 12

adrenalin- prepares body for emergencies, increases heart rate, breathing rate, raises blood sugar levels so that more glucose is available for respiration, diverts blood from gut to limbs

Question 13

EXAMPLES OF HORMONES

what hormone and its function is produced in the PANCREAS

Answer 13

insulin- converts excess glucose into glycogen in liver

glucagon- converts glycogen back into glucose in liver

Question 14

EXAMPLES OF HORMONES

what hormone and its function is produced in the OVARIES

Answer 14

oestrogen- controls ovulation and secondary sexual characteristics
progesterone- prepares the uterine lining for receiving an embryo

Question 15

EXAMPLES OF HORMONES

what hormone and its function is produced in the TESTES

Answer 15

testosterone- controls sperm production and secondary sexual characteristics

Question 16

EXAMPLES OF HORMONES

what hormone and its function is produced in the THYMUS

Answer 16

thymosin- promotes production and maturation of WBCs

Question 17

function of the endocrine system

Answer 17

Regulates activity of the body by controlling hormone secretion and the glands that
secrete them.

Hormonal glands can be stimulated by messages from the nervous system, by other hormones or by receptors located in the particular gland.

Question 18

what do receptors do

Answer 18

detect stimuli in the form of changes outside of

tolerance limits.

Question 19

NERVOUS SYSTEM

• what does it do
• CNS ?
• peripheral? + function

Answer 19

○ Provides the neural pathways by which messages travel in the body and acts as a control centre to coordinate activities that maintain homeostasis.
○ Central nervous system (CNS) → brain and spinal cord
○ Peripheral nervous system → all nerves throughout body that are not part of CNS
○ The peripheral nerves detect stimuli and carry information to and from the CNS by
transmitting messages in the form of electrochemical responses.

Question 20

list 4 features of neuron structures

Answer 20

cell body: nucleus and organelles found in other cells

dendrites: Fine branching extensions of the cytoplasms that receive messages in the form of impulses from other axons and conduct these nerve impulses towards the cell body
axons: Long extensions of cytoplasm that conduct messages away from the cell body

myelin sheath: Fatty insulating substance that surrounds and protects some nerve fibres
- the fatty sheath increases the speed of the nerve impulses along the neuron

Question 21

list and describe the 3 types of neurons

Answer 21

• motor neurons: transfer messages along the CNS to effectors (things that produce a response to specific stimulus such as muscles or glands. short dendrite with long axon)
• interneurons: the link between motor and sensory neurons on the CNS.
  short dendrite with short axon
• sensory neurons: carry impulses from the sensory cells in the PNS to the CNS.
  long dendrite with short axon

Question 22

how do neurons carry signals to and from the CNS

Answer 22

When a stimulus is detected by sensory receptors, sensory neurons (nerve cells) send signal from the sensory receptors to the CNS. CNS coordinates response and sends signal down through a interneuron to a motor neuron. Nerve cells that receive from CNS transfer the signal to the effector. The effectors produce a response to the stimulus.

- Electrochemical impulses involve change in electricial potential of the cell membrane of the axon. (action potential)

Question 23

MECHANISMS IN PLANTS THAT ALLOW WATER BALANCE TO BE MAINTAINED

explain INTERNAL WATER CONTROL via GUARD CELLS AND STOMATA

Answer 23

• Plants control water movement out of leaves to keep stable internal environment

* When water level is high in plants -> guard cells on leaves absorb water and become turgid-> thin outerwalls stretch out and thick inner walls are pulled apart-> stomata open
* Water diffuses out of plant until homeostasis returns 

Low water level-> guard cells become flaccid-> stomata close to prevent water loss-> homeostasis returns -> maintains water balance

Question 24

OTHER STRUCTURES

Answer 24

• Orientation: angling leaves away from the sun at different times of the day reduces the rate of the transpiration
  
  • Smaller leaves: reduces SA to volume ratio -> less SA for transpiration
  • Water storage: succulents survive in dry enviro asthey have fleshy stems and leaves that swell up and retain moisture when its available
  • Regulating openining and closing of stomata: opening stomata at the cooler parts of day and night and closing it during the hotter parts reduces evaporation and therefore minimises water loss
    waxy cuticle: ensures epidermal cells are waterproof, preventing loss of water by evaporation from surface cells