Warm Up 4/14

1.     Describe, using an example, the role of altruistic behavior

§  Altruism is behaviour which benefits another individual at the cost of the performer

§  It appears to be in opposition to natural selection as it reduces the possibility of the altruistic individual passing on their own genes

§  However it improves the chances of the other individual passing on genes into the same gene pool (this is called inclusive fitness)

§  If the individuals are closely related, altruistic genes will persist in the gene pool and be naturally selected

§  Enhancing the reproductive success of relatives is called kin selection

§  Altruism occurs in social animals and is more common in members of the same species who are closely related

Examples of Altruism:

§  Vampire bats commonly regurgitate blood to share with unlucky or sick roost mates unable to gain independent sustenance

§  Velvet monkeys give alarm calls to warn fellow monkeys of predators, even though doing so draws attention to themselves

§  Termites break a gland in their neck, releasing a sticky substance which protects others from attacking ants at the cost of their life

2.     Explain how the sympathetic and parasympathetic systems control the heart, the salivary glands, and the iris of the eye

The sympathetic and parasympathetic nervous systems are part of the autonomic system and have antagonistic actions

Sympathetic Nervous System

§  Involved in processes that prepare the body for action ('fight or flight' responses)

§  The sympathetic nervous system releases noradrenaline (adrenergic) via sympathetic nerves

§  Heart rate will increase to improve blood flow (via release of adrenaline)

§  Pupils will dilate to improve vision (via contraction of radial muscles)

§  Blood flow to gut will decrease (due to vasoconstriction of blood vessels by smooth muscles)

Parasympathetic Nervous System

§  Involved in processes that occur when the body is relaxed ('rest and digest' or 'feed and breed' responses)

§  The parasympathetic nervous system releases acetylcholine (cholinergic) via parasympathetic nerves

§  Heart rate will decrease to reduce blood flow (via stimulation by vagus nerve)

§  Pupils will constrict to restrict light and potential retinal damage (via contraction of circular muscles)

§  Blood flow to gut will increase to facilitate digestion (due to vasodilation of blood vessels by smooth muscles)

3.     Outline how endorphins can act as painkillers

·       Pain is perceived when impulses pass from pain receptors (nocireceptors) in body tissues to sensory areas of the cerebral cortex

·       Endorphins are released by the pituitary gland during stress, injury or exercise and act as painkillers by blocking pain perception

·       They do this by blocking the release of neurotransmitters at the synapses involved in pain signal transmission

4.     Define the term innate behavior

·       Innate behaviour is an instinctive response that is developmentally fixed (i.e. independent of environmental context)

Warm Up 3/27

1.     Define the terms stimulus, response, and reflex in the context of behavior

·       Stimulus:  A change in the environment (external or internal) that is detected by a receptor

·       Response:  A change in an organism (an action) resulting from a stimulus

·       Reflex:  A type of response that is rapid and involuntary (unconscious)

2.     Explain the role of receptors, sensory neurons, relay neurons, motor neurons, synapses and effectors in the response of animals to stimuli

·       Receptors transform stimuli into electrical nerve impulses

·       Sensory neurons relay the nerve impulse to the central nervous system (via the dorsal root of the spinal cord)

·       Relay neurons (also called interneurons or connector neurons) transmit nerve impulses within the CNS

·       Motor neurons receive nerve impulses from the CNS (via the ventral root) and relays the signal to an effector

·       Effectors (muscles or glands) produce a response to the stimulus

·       Synapses are the junctions between two nerve cells and transmission of a signal across these junctions require chemical neurotransmitters

3.     Draw and label a diagram of a reflex arc for a pain withdrawal reflex, including the spinal cord and its spinal nerves, relay neuron, motor neuron and effector

4.     Explain how animal responses can be affected by natural selection, using two examples

Natural selection describes the process by which the frequency of an inheritable characteristic changes as a result of external (environmental) agents

These beneficial inheritable traits (adaptations) can include instinctive behaviours such as migrating, foraging, hunting, communication, etc.

Example:  Blackcap Migration Patterns

§  The blackcap (Sylvia atricapilla) exhibits behavioural variation in its migration patterns from its summer breeding grounds in Germany

§  Historically, most blackcaps migrated south to Spain (warmer climate in winter) with a minority migrating west to the UK (closer, but cooler)

§  With a rise in global temperatures, more blackcaps are now migrating west to the UK (more favourable survival prospects increase allele frequency)

Example:  House Sparrow Feeding Behaviours

§  The house sparrow (Passer domesticus) will chirp and gape as a fledgling in order to be fed by its parents

§  In a nest of chicks, those which chirp louder and gape more obviously are more likely to be fed more and survive longer

§  Hence the alleles responsible for chirping and gaping are passed to offspring increasing prevalence of the behaviour

Warm Up 2/28

1. What are the steps in oogenesis?

• Oogenesis describes the production of female gametes (ova) within the ovary
• The process begins during foetal development, when a large number of cells (oogonia) are formed by mitosis before undergoing a period of growth
• These cells begin meiosis but are arrested in prophase I until puberty
• At puberty, some follicles continue to develop each month is response to FSH secretion
• These follicles complete the first meiotic division to form two cells of unequal size
• The cell with less cytoplasm is a polar body (which degenerates), while the larger cell forms a secondary oocyte
• The secondary oocyte begins the second meiotic division but is arrested in prophase II (until fertilisation)
• It is released from the ovary (ruptured follicle develops into corpus luteum) and, if fertilisation occurs, will complete meiosis
• The second meiotic division will produce an ovum and a second polar body

Overview of Oogenesis

2. What are the steps in spermatogenesis

• Spermatogenesis describes the production of spermatozoa (sperm) in the seminiferous tubules of the testes
• The first stage of sperm production requires the division of germline epithelium by mitosis
• These cells (spermatogonia) then undergo a period of growth
• This is followed by two meiotic divisions that result in four haploid daughter cells
• These haploid cells then differentiate to form sperm cells
• The developing sperm cells are nourished throughout by the Sertoli cells

Overview of Spermatogenesis

3. What are the similarities and differences between the two?

Similarities:

• Both processes result in the formation of haploid gametes
• Both processes involve mitosis, growth and meiosis

Differences:

Warm Up 2/26

11.     A blood clot contains a network of protein.  What is the protein?

·      Fibrin

22.     Outline how the liquid that flows through the proximal convoluted tubule (PCT) is produced.

·      Selective reabsorption

·      Substances are absorbed through microvilli cell lining that increases the surface area of the PCT

·      One substances are actively reabsorbed, they are passively diffused into the bloodstream

·      Mineral ions and vitamins are actively transported via protein pumps or carrier proteins

·      Glucose actively transported across the membrane in symport with sodium

·      Water follows the movement of the ions passively (osmosis)

33.     State the name of the substances reabsorbed by the PCT.

·      Glucose, amino acids, vitamins, hormones, mineral ions, water

44.     Discuss the benefits and dangers of immunization against bacterial and viral infections.

Benefits:

§  Vaccination results in active immunity

§  It can limit the spread of infectious diseases (pandemics / epidemics)

§  Diseases may be eradicated entirely (e.g. smallpox)

§  Vaccination programs may reduce the mortality rate of a disease as well as protect vulnerable groups (e.g. youth, elderly)

§  Vaccinations will decrease the crippling effects of certain diseases (e.g. polio) 

§  It will decrease health care costs associated with treating disease conditions

Risks:

§  Vaccinated individuals may produce (mild) symptoms of the disease

§  There may be human error in the preparation, storage or administration of the vaccine

§  Individuals may react badly to vaccines (e.g. hypersensitive / allergic reactions)

§  Immunity may not be life long - booster shots may be required

§  There may be possible toxic effects of mercury-based preservatives used in vaccines