Unit 2 biology revision

1. Unit 2 biology revision Organism adaptations

2. Quick quiz • Question 1: • For the following behaviours, state whether they are innate or learnt. If learnt, state the type of learning. • A duckling following an object, not only its mother, from an early age. • An orb weaver spider weaving its webs. • A child riding a bike. • Having a clock you don’t notice is ticking. • Salivating when thinking of salt and vinegar chips.

3. 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 • Habituation. • Problem solving • Innate behaviour. • Communication.

4. Question 3: • The type of learning which involves the use of past attempts to modify the result is called • Innate. • Trial and error. • Problem solving. • Conditioning.

5. Questions 4: • An example of an adaptation to maintain temperature in a hot environment in a species of eucalypt could be • The closing of stomata. • An extensive root system. • Leaves which point downwards and direct water to the roots. • The turning of leaves so that they are parallel to the sun, resulting in a reduction of surface area exposed to the sun.

6. Question 5: • After eating a salty meal the hypothalamus (a part of the brain) receives • information from osmoreceptors. The hypothalamus produces antidiuretic • hormone (ADH), which is stored in the pituitary gland. ADH released by the • pituitary acts on the tubules in the kidney to absorb more water. • It would be expected that less ADH would be released • On a hot day. • When nervous. • During exercise. • After blood loss.

7. 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

8. Homeostasis • Homeostasis 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

9. regulatory mechanisms in animals Positive feedback Negative feedback Negative Feedback occurs when the response to the stimulus, decreases the original stimulus. Example: Negative feedback regulates homeostasis in our bodies. • Positive feedback occurs when the response to the stimulus increases the original stimulus. • Example: child brith, and the release of oxytocin

10. 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.

11. Endocrine system- major hormones

12. NERVOUS SYSTEM Peripheral (PNS) Central (CNS) Somatic Autonomic Sensory Brain Spinal cord Sympathetic Parasympathetic The nervous system

13. 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)

14. Types of nervous systems • Autonomic 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)

15. 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. Types of neurons

16. Parts of a neuron Dendrites: 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)

17. 4 parts of the nervous system response • Receptors – detect stimuli • Neurons – transmit impulses • CNS – determines response • Effectors – carry out responses (muscles & glands)

18. Major sense organs • Photoreceptors- Vision • Chemoreceptors – Smell, taste and communication • Mechanoreceptors– Touch, pressure, balance, hearing

19. Endotherm Vsectotherm • 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 • 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.

20. Structural adaptations • To heat up • Colour • Fur • Body size • Body shape • Fat insulation • To cool down • Colour • Skin • Body size • Tongue

21. Behavioural adaptations • To heat up • Basking • Huddling together • Hibernating • Nocturnal behaviour • Vigorous activity • Increase clothing • Burrowing • To cool down • Bathing • Seeking shade • Burrowing • Drinking water • Inactivity

22. Physiological adaptations • To heat up • Shivering • Increased metabolism • Hibernation • Counter current heat exchange • To cool down • Secretion of Sweat • Vasodilation of the blood vessels • Redistribution of blood- increased blood flow to skin

23. OsmoconformersVsosmoregulators • Osmoregulators tightly regulate their body osmolarity, • Always stays constant • E.g. freshwater fish • Osmoconformers match their body osmolarity to their environment • Can be either active or passive • E.g. marine animals

24. Plant tropisms • A 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

25. 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

26. Plant adaptations in various environments • Halophytes • Lover’s of salt • Physiological adaptations: • Higher osmotic pressure • Exclusion of salt from leaves • Return of salt to roots • Shedding of slat-laden leaves • Excretion of salt from salt glands • Xerophytes • Lover’s of dryness • Structural adaptations: • Thick cuticles • Hair covering leaves • Few stomata • Sunken stomata • Reduced leaf surface A:V • Changes orientation of leaves