{Influences on life}

BIOLOGY 1

CLASSIFICATION AND NAMING SPECIES

King Philip Came Over For Good Spaghetti

All living things belong to one of the five groups called kingdoms:

- Animalia are multicellular; cell do not have chlorophyll or a cell wall; they feed heterotrophically (find food from their environment)

- Plantae are multicellular; cells have chlorophyll and a cellulose cell wall; they obtain food autotrophically (make food by photosynthesis)

- Fungi are multicellular; cells do not have chlorophyll; they feed saprophytically (on dead organic matter)

- Proctoctista are unicellular (except seaweed), with a distinct nucleus.

- Prokaryotes (a.k.a bacteria) are unicellular, but without a distinct nucleus. simple cell structure with no nucleus. Examples are cholera, dysentery, tuberculosis

- Viruses do not belong to a kingdom because scientist cannot decide weather they are living organisms as they are considered not alive. Reproduce inside a host cell. Examples are influenza, mumps, measles and AIDS.

• SpeciesA group of organisms with similar characteristics, which can

successfully interbreed to produce fertile young.

B1.2 VERTEBRATES AND INVERTEBRATES

The way they absorb oxygen!-gills like fish and young amphibians?-lungs like mammals reptiles and birds?-through their skin like adult amphibians?

How do they reproduce / give birth?-external fertilisation-Internal fertilisation (inside body)-Lays eggs; oviparous-Gives birth to live young; viviparous e.g. mammals

Are they homoeothermic or poikilothermic?-homeotherm; body temperature kept constant-poikilotherm; body temperature varies with surroundings

◊ Hybrids are neither one species not another , and show characteristics of both parents.

◊ Hybrids are usually infertile but not always ◊ Many plant hybrids are fertile

◊ Being infertile means they are unlikely to have offspring of their own and pass on their mix of characteristics.

◊ Not all organisms reproduce sexually (some produce asexually)

B1.3 SPECIES

◊ All organisms have a two-part binomial name.

◊ Homo sapiens, Homo is our genus name, sapiens is our species

name.◊ The binomial naming system is

used because it prevents confusion

◊ Binomial classification is important because it enables

scientists to:» Communicate information about

thousands of different species» Recognise areas of great

biodiversity that should be targets for conservation efforts.

◊ A ring of populations encircles an area of unsuitable habitat.

◊ At one location in the ring of

populations, two distinct forms coexist without

interbreeding, and hence are different

species.◊ Around the rest of

the ring, the traits of one of these species change

gradually, through intermediate

populations, into the traits of the second

species

RING SPECIES◊ Famous examples of ring species are;◊ the herring and  lesser black-

backed gulls in northern Europe◊ and the Ensatina salamanders of

California.

◊ Differences in characteristics are called variation.◊ There is variation within a species but much more between different

species.◊ This variation within a species can make classification difficult.

B1.4 VARIATION

Accurate classification using the binomial system allows biologists to:

◊ Easily identify existing and new species

◊ See how organisms are related

◊ Identify areas of greater and lesser biodiversity.

◊ Biodiversity is important because we obtain many products from living things e.g. Food,

medicine

B1.5 VARIATIONDifferent genes cause genetic

variation◊ All plants and animals have

characteristics that are in some way similar to their parents

◊ This is because an organism’s characteristics are determined by the genes inherited from their parents .

◊ Most animals get some genes from the mother and some from the father.

◊ The combining of genes from two parents causes genetic variation. (no two of the species are identical other than identical twins)

◊ Some characteristics are determined only by genes (e.g. A plant’s flower colour)

◊ In animals these include: eye colour, blood group, and inherited disorders (e.g. Haemophilia or cystic fibrosis )

Characteristics are also influenced by the environment.

» Environmental variation is any differences caused by the

conditions someone lives in.» Most characteristics are due to

genes and the environment.

Variation can be either continuous or discontinuous

§ In continuous variation, characteristics are spread over a range of values. Height in humans is an example

- Tongue rolling is an characteristic that shows discontinuous variation. There are no intermediates.

◊ All organisms are adapted to their surroundings – they have variations in their characteristics that enables them to

survive in their habitats

B1.6 REASONS FOR VARIETY

◊ Polar bear adaptations ◊ If a characteristic shows continuous variation and a large enough number of individuals are measured, when plotted we get a graph with a particular shape.

◊ This shape is called a normal distribution curve (a.k.a bell curve.)

◊ It shows that most individuals within the middle part of the range in variation, and there are fewer individuals with measurements at the extremes of the range.

◊ Charles Darwin was the first person to propose how evolution takes place through natural selection.

◊ He described his ideas in a book titles On the Origin of Species, published in 1859.

B1.7 EVOLUTIONIdeas central to Darwin’s theory.

∞ There is variation in characteristics between individuals of the same

species∞ Overproduction means that organisms

produce more offspring than will survive till adulthood.

∞ There is a struggles for existence, or competition, between individuals

and resources.∞ Individuals better adapted will survive to pass on their advantageous

traits survival of the fittest.∞ Individuals less suited for

competition may become extinctThe result of individuals becoming more

suited to a particular way of life means that over time new species

emerge –speciation-.

You can see this in the many different species of birds that developed from a common ancestor. The change is

called evolution

◊ Speciation (the formation of new species) provides evidence for the natural selection of organisms.

◊ Geographical isolation is one way speciation occurs, e.g. One side of a newly formed mountain range might be wetter and colder than the other side.

◊ over many generations, the part of the population on the colder side change through natural selection (so they can survive the harsher climate).

◊ Eventually the difference in characteristics is so great that the population living in the harsher climate becomes a new species

◊ Inherited characteristics are controlled by genes, which are

sections of chromosomes, chromosomes are long molecules of DNA tightly wound around

proteins.◊ Genes enables cells to make

proteins, which result in characteristics such as eye

colour and leg length.◊ Each sperm and egg contain only half set of chromosomes- in the case of humans this

means 23 (human cells have 46 chromosomes)

◊ When the gametes fuse during fertilisation, the half-set of

chromosomes from the male pairs up the half set of

female chromosomes to form a full set

B1.8 GENES◊ Each chromosome in a pair carries

the same genes in exactly the same place (locus)

◊ An allele is one form of a gene.◊ If the alleles of a pair are the

same, the individual is homozygous for the characteristic

◊ If the alleles are different, the individual is heterozygous.

◊ An allele may be dominant or recessive. Dominant alleles mask the effects of a recessive allele.

◊ Pedigree charts show the way

characteristics of related individuals

pass from one generation to the

next.◊ They provide helpful information about the lineage of lineage of plants and animals,

which is important to farmers.

B1.9 EXPLAINING INHERITANCE◊ The alleles in an organism are its genotype.

◊ What characteristics are expressed is its phenotype.◊ The possible genotypes produced when two organisms breed can

also be shown in a punnett square.

Sickle cell disease◊ A co-dominant disease◊ Symptoms: tiredness, painful joints and muscles, fever, anaemia,

jaundice, sudden pain known as sickle cell crisis caused by sickled red blood cells forming clumps in the bloodstream, blocking blood flow to organs and causing organ damage.

◊ Cause:a mutation that alters haemoglobin molecules and causes them to absorb less oxygen. This also results in the red blood cells becoming sickled shaped.

◊ treatments: medication, lots of fluids and blood transfusions.

B1.10 GENETIC DISORDERS

Cystic fibrosis ◊ Recessive disease◊ Symptoms: breathing difficulties, lung infections, malnutrition,

infertility, lung infections because of bacteria becoming trapped in the mucus, bone disease.

◊ Cause: overproduction of thick sticky mucus which blocks the air passages, gut and pancreas.

◊ Treatments: physiotherapy and massage, medication, and a nourishing diet.

§ Thermoregulation ;the regulation of body temperature (37°C) § Glucoregulation; the regulation of blood-glucose levels.§ Osmoregulation; the regulation of water in the body.§ Negative feedback; the process by which homeostasis works:

stimulus - receptor - control centre - effector – response.§ Hypothalamus; the part of the brain which controls body

temperature and other things

B1.11 HOMEOSTASIS

§ Vasodilation; blood vessels close to the surface of the skin widen (in order to lower body temperature, by heat being radiated out into environment).

§ Vasoconstriction; blood vessels close to the surface of the skin contract (in order to reduce heat loss, to warm up)

When the body get’s too hot§ Vasodilation; heat is radiated out into surroundings from blood

flow closer to the skin.§ Sweat glands secrete sweat, which evaporates and transfers heat

energy from the skin to the surroundings, it also absorbs heat energy from the skin and so cools it.

§ Hairs lay flat to prevent heat from being trapped

B1.11 HOMEOSTASIS

When it’s too cold.§ Hypothalamus detects drop in temperature.§ Initiates negative feedback mechanism.§ Erector muscles raise hair so an

insulating layer of air is trapped, which warms the body up.

§ Blood flow to the surface of the skin is restricted by narrowing blood vessels to reserve heat.

§ Muscles vibrate to generate heat energy from movement.

B1.12 SENSITIVITY

§ Sensory neurones; carry nerve impulses from the receptors to the CNS. They have long dendrons and short axons§ Motor neurones; carry nerve impulses from the CNS to the effectors. Many short dendrons and one long axon

§ Relay neurones; carry nerve impulses inside the CNS from sensory neurones to motor neurones. Short dendrons and axons.

§ the order of stages in a reflex arc:§ Neurone ➳ relay neurone ➳ motor

neurone ➳ effector§ Synapses are gaps that exist between

neurones

B1.13 SKIN SENSITIVITY§ stimuli and responses are linked by the nervous system in

the following pathway

stimulus➜receptor ➜ sensory neurone ➜ CNS ➜motor neurone ➜ effector ➜ response

§ the involuntary behaviour of a person pulling their foot away after stepping on a pin is known as a reflex response.§Reflex responses are automatic and usually fast, they help to protect the body from damage.§A reflex response is brought about by a chain of nerves called a reflex arc

B1.14 RESPONDING TO STIMULI§ Myelin sheath; insulating envelope that surrounds an axon, helps

with speeding up of electrical impulse travel.

§ Synapse; a small gap where one neurone connects to another.

§ Dendrites; the tiny branches of dendrons which are connected to cells

§ Axons; branches which convey the electrical impulses away from the cell body

§ Neurotransmitters; chemicals that transmit impulses across synapses

B1.15 HORMONES§Pancreas; an endocrine gland: controls blood sugar levels using insulin and glucagon§Adrenal glands; an endocrine gland: Produce adrenaline to speed up the heart rate and speed up responses to stimuli.§Pituitary gland; an endocrine gland: release anti-diuretic hormone (ADH) which conserves water in the body by making the kidneys produce more concentrated urine§Endocrine glands; parts of the body which produce hormones§Target organ; an organ that responds to a certain hormone

B1.16 DIABETES§ Insulin; a hormone released by the pancreas which reduces the blood sugar level by causing the liver to turn glucose into glycogen.§ Glycogen; a store of glucose in the liver.§ Glucagon; a hormone released by the pancreas which increases the blood sugar level by causing the liver to turn glycogen into glucose.§ BMI; a measurement that uses a person's weight and height to determine if they are of a healthy weight.§ The pancreas monitors the level of blood glucose and triggers a response to return the levels to normal if they change.

Type 1 diabetes◊ Between 5 and 10% of diabetics have Type 1 diabetes.◊ When the pancreas does not produce insulin.◊ Is controlled by injecting manufacture insulin to reduce the blood sugar level, and avoiding foods that contain lots of glucose

Type 2 diabetes◊ Either cells/target organs don't respond to insulin, or the person becomes immune to the effects of the hormone. ◊ Is controlled by eating a healthy diet, having regular exercise and losing weight.◊ Obesity increases risk of type 2 diabetes as well as age and lack of exercise.

B1.17 TROPIC RESPONSES Plant growth hormones◊ Positive tropism; growth towards a stimulus◊ Negative tropism; growth away from a stimulus◊ Phototropism; a growth towards light.◊ Gravitropism; a growth downwards (positive) or upwards (negative) in response to gravity.◊ Auxins; plant growth hormones which control growth at the tips of shoots and roots.◊ Gibberellins; plant growth hormones which stimulate seed germination, stem growth and flowering.◊ Uses of gibberellins; weedkillers, rooting powder for cuttings, controlled ripening of fruits while in transportation or in shops, applying them to unpollinated flowers so the fruit grows but not the seeds

B1.18 PLANT HORMONES Phototropism◊ plants roots are negatively phototrophic (move away from light)◊ plants shoots are positively phototrophic,(move towards light) to get enough light for photosynthesis. ◊ positive phototropism is caused by plant hormones called auxins.◊ auxins are produced in the tip of a shoot, where they cause elongation of the cells.◊ concentration of auxin is higher on shaded side of shoot so that shoot bends towards light.◊ root tropism works in similar but reversed ways, concentration of auxins would be higher in underside of root so roots can seek out minerals to grow.◊ roots show positive gravitropism◊ gibberellins, initiate germination (the first emergence of a shoot) by causing starch stored in seed to be turned into sugars that the seed uses for energy to grow.◊ gibberellins also stimulate flower and fruit production in some plant species.

B1.19 USES OF PLANT HORMONES Selective weed killers◊ artificial auxin is used as a selective weed killer because it only makes plants with broad leaves over grow without effecting produce.

Rooting powder◊ synthetic auxins are also used in rooting powders.◊ plants cuttings are dipped in rooting powder, which makes them develop roots more rapidly.◊ large numbers of the same plant can be produced quickly using cuttings compared to growing from seeds

Seedless fruits◊ some seedless fruits are produced using plant hormones.◊The flowers are sprayed with plant hormones that cause fruit to develop but not seeds.◊ fruits like seedless grapes are sprayed with gibberellins to increase size.

Fruit ripening◊ plant hormones naturally control the ripening of fruits. ◊ farmers can make use of this and control when ripening occurs. plant hormones are sprayed onto• fruit trees to stop fruit from falling

and getting damaged• fruit trees to speed up ripening, all

the fruit ripens quicker and can be picked in one go

• Unripe fruit to make them ripe• a plant hormone called ethene gas is released onto fruit so they ripen just

in time to be delivered to shops

B1.20 EFFECTS OF DRUGS&

B1. 21 REACTION TIME AND DRUGS

◊ Addictive; your body is physically dependent on it◊ reaction time is how long it takes for a person to respond to a stimulus.◊ this depends on how quickly and how much neurotransmitter is released.◊ Inhibition; restraint of a behavioral process, a desire, or an impulse

◊ painkillers; such as morphine deaden pain, block nerve impulses so we feel less pain.◊ hallucinogens; like cannabis, magic mushroom, LSD and solvents, produce sensations of false reality called hallucinations, changes the way the brain works. This distorts our senses of colour, time and space.◊ stimulants; including caffeine, increase the speed of reaction times, increases speed of neurotransmission across synapse.◊ depressants; such as alcohol slow down activity of the brain and reaction times.◊ Narcotic; drug that makes you feel sleepy

B1.22 THE DAMAGE CAUSED BY SMOKING

Tobacco contains many chemical substances that damage living tissue.◊ Tar; coats the lining of the lungs making them less able to take in oxygen, and also contains carcinogens (causes cancer)◊ Carbon monoxide; a poisonous gas which reduces the capacity for red blood cells to carry oxygen by permanently attaching to haemoglobin.◊ nicotine is the addictive part of tobacco and makes it hard to give up.

B1.23 THE EFFECTS OF ALCOHOL

Short-term effects of alcoholSlower reflexes, blurred vision, lower inhibitions.

Long term effects of alcohol• Liver cirrhosis; Over-consumption of alcohol causes the death of liver cells, forming scar tissue that blocks blood flow. This leads to toxic substances building up in the body.• reduced fertility• brain damage

B1.24 ETHICS AND TRANSPLANTS

• Donor; the person donating the healthy organ for the transplant• Ethical Decision; a decision made to reach an answer that is fair based on what you think is right and wrong.• there are many moral and ethical issues.-Weather it is right to use animals- weather money should be an incentive in a decision to donate organs.- wider human right (transplant tourism)

In a transplant, a healthy organ such as a heart or liver is taken from one body (the donor) and put into a patient to replace an organ that no longer functions properly

B1.25 - .27• Antiseptic; chemical substances that kill pathogens outside the body. Usually found in sprays or gels.• Antibacterial; chemical substances that kill bacteria outside the body. Found in hand washes.• Antibiotic; a substance used to treat a bacterial infection inside the body.• Antifungal; a substance used to treat a fungal infection inside the body• Resistant; bacteria that is no longer effected by an antibiotic.• MRSA; an antibiotic resistant bacteria• infectious disease are those caused by pathogens that spread from person to person.•Cholera bacteria are found in water contaminated with sewage.• viruses that cause colds and flu are airborne.• salmonella is a type of food poisoning that comes from chicken. Cooking food thoroughly and good hygiene decreases the risk of getting salmonella.• HIV is a virus that causes AIDs, it destroys white blood cells that contribute to the immune system.•Athlete's foot is a fungal infection that can be spread through contact. •The bacteria that cause diarrhoea produce endotoxins (poisons).

B1.25 - .27• Physical Barrier; A barrier that stops pathogens getting into the body. Examples are skin and blood clotting• Chemical Barrier; a barrier that kills pathogens before they can harm us. Examples are lysozymes in tears and stomach acid.• The skin, or epithelial surface, serves as the primary barrier to microbial entry into the body; skin peeling, drying out, and the skin's acidity all serve to dislodge or kill foreign pathogens.•Orifices such as the eyes and mouth, which are not covered by skin, have other mechanisms by which they prevent entry; tears wash away microbes, while cilia in the nasal passages and respiratory tract push mucus (which traps pathogens) out of the body.•Many chemical barriers also exist once pathogens make it past the outer physical barriers; the acidity of the stomach ensures that few organisms arriving with food survive the digestive system.

B1.28 INTERDEPENDENCE AND FOOD WEBS

• Biomass; The total mass of organic matter comprising a group of organisms in a particular habitat • Predator; an animal which kills and eats an animal• Prey; the animal hunted and killed by its predator• Population; the numbers of a particular species in a particular ecosystem• Interdependent; animals that depend on each other for food• Trophic Level; each step in a food chain or web•Food Chain; a series of steps in which organisms transfer energy by eating and being eaten• Secondary Consumer; a carnivore; an organism which feeds on the primary consumer.• Primary Consumer; a herbivore; an organism that eats plants or other autotrophs.• Producers; plants which make their own food in photosynthesis.•Pyramid of number; pyramid which shows the number of organisms at each trophic level.• Pyramid of Biomass; pyramid which shows the total dry mass of organisms at each trophic level• Parasitism examples; dog & fleas, head lice & human, tapeworm & human, mistletoe & tree.• Mutualism examples; oxpecker & buffalo, cleaner fish & large fish, nitrogen-fixing bacteria & legume, chemosynthetic bacteria & giant tubeworms

B1.29 PARASITES AND MUTUALISTS• Host; the larger participant in a host-parasite relationship, serving as home and food source for the smaller parasite• Parasite; an organism that feeds on the cell contents, tissues, or body fluids of another species (the host) while in or on the host organism. Parasites harm but usually do not kill their host• Mutualism; an relationship in which both organisms benefit

• bacteria that can turn gaseous nitrogen into nitrogen compounds are called nitrogen-fixing bacteria. Some live in the root nodels of leguminous plants•The bacteria are protected from the environment and obtain chemical substances from the plant which they use as food.•The plant gets nitrogen compounds which it uses for growth.

• chemosynthetic bacteria are producers that get their energy from chemical substances rather than from light.•Some live inside giant tubeworms •The tubeworms gather the chemical substances that the bacteria need for chemosynthesis and tubeworms feed on substances made by the bacteria.• chemosynthetic bacteria is given protection in return

B1.30 POLLUTION &B1.31 POLLUTANTS AND PLANT GROWTH• Chemicals that are harmful to our health and wildlife are called pollutants. These can be released into the environment causing pollution.• nitrates and phosphates are pollutants in fertilisers, which are used to increases crop yield, which can lead to eutrophication.•Which is when the nitrates and phosphates leach out into water causing an algal bloom hence blocking sunlight from reaching the bottom , and preventing the aquatic plants at the bottom form photosynthesizing and reducing oxygen availability for other aquatic life, eventually the plants die from not being able to photosynthesise and symbiotic bacteria feed on them whilst further reducing oxygen availability as they respire, hence leading to other aquatic life e.g. Fish to die• the more polluted a river is with sewage, the less oxygen these is in solution because of eutrophication. Fewer species survive in the polluted parts.• scientists use these indicator species to assess pollution levels.• Freshwater Shrimp; show that that water is clean and free of pollutants•Stonefly Larvae; show that the water is clean and free of pollutants• blood worms; show water is polluted•Sludge worms; show water is polluted (as they survive in areas of low oxygen)

B1.32 INDICATOR SPECIES

•Green Lichens; show that the air is free of Sulfur Dioxide.•Yellow Lichens; show that the air is heavily polluted with Sulphur Dioxide.•Black spot fungus is an infection on roses that show less pollution, as they die in high levels of sulphur dioxide

• sulfur + oxygen = sulfur dioxide• pollution with sulfur dioxide reduces air quality and dissolves in water vapour to form acid rain, which passes into lakes and rivers.• acidic water kills fish• lowers soil pH

B1.33 THE CARBON CYCLE •Carbon is recycled as carbon dioxide (CO2) through respiration and photosynthesis in the carbon cycle.• plants absorb CO2 from the environment which enables them to produce sugars through photosynthesise.•The sugars can be used to form other carbohydrates and proteins that build up plant bodies.• when plants are eaten by animals the carbon in plant tissues become a part of animal bodies, transfer of carbon continues through food chain.• during respiration organisms release carbon dioxide into the air as well as combustion of fossil fuels• chalk is formed from the fossilised remains of dead sea creatures exposed to rain, the chalk dissolves and more carbon dioxide is released.• carbon dioxide is returned to the atmosphere through combustion of fossil fuels and animals, and decomposers respiring.

B1.33 THE NITROGEN CYCLE • Nitrogen Cycle; natural process by which nitrogen, either from the atmosphere or from decomposed organic material, is converted by soil bacteria to compounds that can be assimilated by plants.• Urea; a soluble nitrogenous waste produced in the liver by a metabolic cycle that combines ammonia with carbon dioxide.• Nitrogen Fixing Bacteria; bacteria that fix nitrogen gas into ammonia.• Nitrifying Bacteria; bacteria that convert ammonia to nitrates• Denitrifying Bacteria; bacteria that convert nitrates to ammonia

•Nitrogen fixation decomposition nitrification denitrification ➮ ➮ ➮