unit 2 biology revision

UNIT 2 BIOLO

GY REVISION

O R G A N I SM A

D A P T A T I ON S

QUICK QUIZ Question 1:For the following behaviours, state whether they

are innate or learnt. If learnt, state the type of learning.

 1. A duckling following an object, not only its mother,

from an early age.2. An orb weaver spider weaving its webs.3. A child riding a bike.4. Having a clock you don’t notice is ticking.5. Salivating when thinking of salt and vinegar chips.

Question 2:A classroom aquarium contains goldfish. When the

glass is tapped by students the fish scatter. After many weeks of a school term the fishes’ response has reduced to the point that there is no response. This loss of response is called

A. Habituation. B. Problem solvingC. Innate behaviour. D. Communication.

Question 3:The type of learning which involves the use of

past attempts to modify the result is called

A. Innate. B. Trial and error. C. Problem solving. D. Conditioning.

Questions 4: An example of an adaptation to maintain temperature in a

hot environment in a species of eucalypt could be

A. The closing of stomata. B. An extensive root system. C. Leaves which point downwards and direct water to the roots. D. The turning of leaves so that they are parallel to the sun,

resulting in a reduction of surface area exposed to the sun.  

Question 5:After eating a salty meal the hypothalamus (a part of the

brain) receivesinformation from osmoreceptors. The hypothalamus produces

antidiuretichormone (ADH), which is stored in the pituitary gland. ADH

released by thepituitary acts on the tubules in the kidney to absorb more

water.It would be expected that less ADH would be released

A. On a hot day. B. When nervous. C. During exercise. D. After blood loss.

ADAPTATIONS The characteristics that help a species survive in an

environment are passed on to future generations.

Physical/Structural – the shape and structure of an organism eg. Wings to fly

Behavioural – the behaviour and actions of an animal eg. Basking in the sun to warm body

Physiological – the function of body parts eg. The kidneys and excretory system to conserve water

HOMEOSTASISHomeostasis is the maintenance of a stable

internal environment.

Homeostasis allows species to live in extreme conditions and to extend their geographic range

Regulated by negative feedback systems

REGULATORY MECHANISMS IN ANIMALS

P O S I T I V E F E E D B A C K

Positive feedback occurs when the response to the stimulus increases the original stimulus.

Example: child brith, and the release of oxytocin

N E G A T I V E F E E D B A C K

Negative Feedback occurs when the response to the stimulus, decreases the original stimulus.

Example: Negative feedback regulates homeostasis in our bodies.

THE ENDOCRINE SYSTEM • The endocrine glands produce hormones.• A hormone is a chemical substance that is

secreted directly into the bloodstream and transported to another organ.

• Hormones are produced in endocrine glands or cells with an endocrine function

• They travel in the general circulation or interstitial fluid

• Hormones have an effect on specific body tissues – called target cells.

ENDOCRINE SYSTEM- MAJOR HORMONES

THE NERVOUS SYSTEM

NERVOUS SYSTEM

Peripheral(PNS)

Central(CNS)

Brain Spinal cordSomatic Autonomic

Sympathetic

Parasympathetic

Sensory

TYPES OF NERVOUS SYSTEMS Sensory nervous system- (from PNS to CNS) Send messages from receptors to the brain or spinal

cord E.g. sense of touch, top stove, pin prick (Senses)

Somatic nervous system- (from CNS to PNS) They conduct a response instruction from the CNS to

effector muscles, organs. E. g. Walking, talking, manipulating fingers (Voluntary actions)

TYPES OF NERVOUS SYSTEMSAutonomic nervous system - Controlled by the CNS Concerned with the regulation of movements that do

not normally require conscious thought Regulate internal environment E.g. Heart beat, breathing, release of digestive juices (Involuntary actions)

TYPES OF NEURONS• Sensory neurons-• Sense a change in external or internal environment• Conduct information from receptors to the CNS

• Motor neurons• Leave the CNS and stimulate muscles or glands of the body. • They transport the response to a muscle that can effect the

response.• They “motorise” the muscle or gland to produce a response.

• Interneurons- • Found in the CNS and connect various neurons together.

PARTS OF A NEURONDendrites: receive signals from receptors or other cells and transmit these to the cell body.

Cell body: contains the cell nucleus. Regulates and coordinates signals.

Axon: transmits an electrical impulse to the nerve endings.

Dendrites Cell body Axon (DCA)

4 PARTS OF THE NERVOUS SYSTEM RESPONSE

1. Receptors – detect stimuli

2. Neurons – transmit impulses

3. CNS – determines response

4. Effectors – carry out responses (muscles & glands)

MAJOR SENSE ORGANSPhotoreceptors- Vision

Chemoreceptors – Smell, taste and communication

Mechanoreceptors– Touch, pressure, balance, hearing

Endotherms- • generate large

amount of heat by internal heat production

• Contain insulting structures to help slow loss of heat

• Use physiological mechanisms and behaviour to regulate loss of metabolic heat.

Ectotherms- • are unable to raise their

body temperature by internal heat production

• Produce less heat• They lose heat to the

environment faster• They use less energy • Cell function slows at low

temperature, which means often are inactive during winter

ENDOTHERM VS ECTOTHERM

To cool down

• Colour• Skin• Body size• Tongue

To heat up

• Colour• Fur• Body size• Body shape• Fat insulation

STRUCTURAL ADAPTATIONS

To cool down• Bathing• Seeking shade• Burrowing• Drinking water• Inactivity

To heat up• Basking• Huddling together• Hibernating• Nocturnal behaviour• Vigorous activity• Increase clothing• Burrowing

BEHAVIOURAL ADAPTATIONS

To cool down

• Secretion of Sweat• Vasodilation of the

blood vessels• Redistribution of

blood- increased blood flow to skin

To heat up

• Shivering• Increased metabolism• Hibernation• Counter current heat

exchange

PHYSIOLOGICAL ADAPTATIONS

• Osmoconformers match their body osmolarity to their environment

• Can be either active or passive

• E.g. marine animals

• Osmoregulators tightly regulate their body osmolarity,

• Always stays constant

• E.g. freshwater fish

OSMOCONFORMERS VS OSMOREGULATORS

PLANT TROPISMSA tropism is an involuntary growth response to

an external stimuli Photo - light Geo - gravity Thigmo – touch Hydro – water

Positive tropisms grow towards the stimulus.

Negative tropisms grow away from the stimulus

EFFECTS OF AUXIN A hormone in plants called Auxins controls

these tropisms.

Auxin is a growth hormone that causes the cell to elongate or lengthen

Xerophytes • Lover’s of dryness• Structural adaptations:1. Thick cuticles2. Hair covering leaves3. Few stomata4. Sunken stomata5. Reduced leaf surface

A:V6. Changes orientation of

leaves

Halophytes • Lover’s of salt• Physiological adaptations:1. Higher osmotic pressure2. Exclusion of salt from

leaves3. Return of salt to roots4. Shedding of slat-laden

leaves5. Excretion of salt from salt

glands

PLANT ADAPTATIONS IN VARIOUS ENVIRONMENTS