Bio paper 2

• the main function of the nervous system is to control, coordinate and respond to stimuli
• the central nervous system consists of the brain and spinal cord
• the peripheral nervous system consists of nerves that connect the CNS with other parts of the body
• the main function of the nervous system is to control and coordinate all activities within an organism
• neurons have three parts - dendrites, cell body and axon
• nervous tissue consists of neurones which are specialised cells that transmit electrical impulses
• there are two types of neurons - sensory (afferent) and motor (efferent)
• the autonomic nervous system controls involuntary actions such as heart rate and digestion
• the somatic nervous system controls voluntary movements
• dendrites are used to receive messages from other neurones or sensory receptors
• glial cells support and protect neurones
• neurons are specialised cells which transmit electrical signals called action potentials along their axon
• What is the definition of an ecosystem?

  The living and non-living parts of a habitat and how they interact together.
• What is a community?

  All the living organisms living in the same area.
• What is a population?


  All of the individuals of one species which live in the same area.
• What is interdependence?


  Within a community each species depends on other species for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community.
• What is the definition of a species?

  Individuals of the same species can interbreed to produce fertile offspring.
• What is an abiotic factor? Give examples.

  A non-living part of the environment. Such as light intensity, temperature, moisture levels, soil pH, wind intensity etc.
• What is a biotic factor? Give examples.

  Living factors in an ecosystem. Such as availability of food, new predators, new pathogens, one species out-competing another.
• What is an adaptation?


  A feature that helps an organism survive in their environment. May be structural, behavioural or functional.
• What is an extremophile?


  Organisms that live in very extreme conditions such as high temperature or salt concentration. Eg bacteria in deep sea vents.
• What is a method for random sampling?

  Using a random number generator to generate coordinates for placing a quadrat randomly. Count the number of the species of interest in the quadrat. Repeat several times and calculate a mean.
• What is a transect?


  Method to investigate the change in distribution of a species across a habitat. Place a tape measure across a habitat and place quadrats down at regular intervals and count the number of the species of interest in each quadrat.
• What is the role of microorganisms in the carbon cycle?

  Microorganisms decompose dead organisms and waste. They return carbon dioxide to the atmosphere as they do respiration.
• What is the definition of biodiversity?

  Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem.
• Give examples of pollution of water/air/land

  · In water: sewage, fertiliser or toxic chemicals

  · In air: from smoke and acidic gases

  On land: from landfill and from toxic chemicals.
• What are uses of peat bogs? What does their removal lead to?

  Uses: burnt as a fuel. Garden compost.

  Destruction reduces the area of habitat

  Decay or burning of peat releases CO2 into atmosphere.
• How can biodiversity be maintained?

  · Breeding programmes for endangered species

  · Protection and regeneration of habitats

  · Reduction of deforestation

  · Recycling instead of landfill

  Reintroduction of field margins and hedgerows
• What is the definition of homeostasis?

  the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
• Compare the endocrine system (hormones) with the nervous system?

  Hormones travel in the blood, nerve impulses travel in neurones. Hormones are slower than nerve impulses. Hormones are longer lasting than nerve impulses.
• Where is the thyroid gland? What does it release?

  In the neck. Releases Thyroxine which stimulates basal metabolic rate and is important in growth and development.
• Where is the pituitary gland? What is it's role?

  In the brain. Is the master gland - controls other glands. Releases FSH and LH.
• Where is the pancreas? What hormones does it release?

  In the abdomen (near stomach). Releases insulin and glucagon.
• Where is the adrenal gland? What does it release?

  Above the kidneys. Release adrenaline which brings about the fight or flight response
• When blood glucose is too high....

  The pancreas releases insulin. Stimulates glucose to be taken in my cells in muscles and the liver. Excess glucose stored as glycogen. Blood glucose is lowered.
• When blood glucose is too low...

  The pancreas releases glucagon. Stimulates the liver to break down glycogen into glucose and release it into the blood. Blood glucose is raised.
• What is the definition of a hormone?

  A chemical messenger which travels in the blood to target organs.
• What is type 1 diabetes?

  A disorder in which the pancreas cannot produce insulin. Causes uncontrolled high blood glucose. Treated with insulin injections.
• What is type 2 diabetes?

  Cells no longer respond to insulin. Obesity is a risk factor. Controlled my management of diet.
• What is a reflex?

  Reflex actions are automatic and rapid. They do not involve the conscious part of the brain.