Biology

  • Smoking and Health
  • Adaption and Competition
  • Cells
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  • Created by: Louisa C
  • Created on: 30-12-08 13:55

Smoking

What's in a cigarette?

1) Nicotine-

  • addictive drug- makes it hard to give up cigarettes
  • stimulant, so increases heart rate- can lead to high blood pressure and heart disease

2) Carbon Monoxide-

  • colourless andodourlesspoisonous gas
  • combines irreversibly withhemoglobinin your red blood cells- reduces the amount of oxygen carried in the blood
  • especially dangerous for pregnant women as it reduces the amount of oxygen getting to the foetus

3) Tar-

  • contains many carcinogens (cancer-causing chemicals)
  • stickyblacksubstance which lines the alveoli in the lungs and makes gas exchange more difficult (reducesthe surface area of the lungs)
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Smoking and Health

1) Lung Cancer-

  • caused by carcinogens in tar
  • cells in your lungs divide out of control & form atumourwhich can spread to other tissues in your body

2) Emphysema-

  • chemicals in cigarette smoke destroy the walls of the alveoli (air sacs)
  • leaves less surface area for gas exchange and breathing becomes much more difficult

3) Bronchitis-

  • chemicals in cigarette smoke destroy the cilia (tinyhairs) that line the wind pipe
  • mucus which is normally removed by the cilia accumulates & slides down the lungs
  • coughing to attempt to remove this mucusinflamesthebronchi
  • bacteria in the mucus can cause infection

Other diseases caused by smoking include: carbon monoxide poisoning, high blood pressure & heart disease, loss of limbs

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Competition in Animals

What animals compete for:

  • Water
  • Territory
  • Mates

Adaptions useful for plant-eaters, to find food:

  • A wide-range of diet
  • Long necks, or strong teeth, for reaching and chewing leaves

Adaptions useful for carnivores, to find food:

  • Long legs, for fast running
  • Sharpeyes to spot prey

Prey compete among themselves, to not be caught by the predators:

  • Camouflage colouring
  • Goodhearing, to pick up a predators approach
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Competition in Plants

Plants compete with each other for:

  • Light
  • Water
  • Nutrients (minerals) from the soil

Why?

  • Big, tall plants take up a lot of water and minerals from the soil and prevent light from reaching plants beneath them
  • If aplantsheds its seeds, and theylandnearby, theparentplant will be in competition with its own seedlings
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Coping with competition

Competition from bigger plants:

  • Small plants often grow and flower early in the year, so they get plenty of light while thebiggerplants' branches are bare
  • The lost leaves from the bigger plant, rot and provide extra minerals in the soil
  • The dormant, larger plant does not take in as much water- some small plants also have special roots which allow them to search deeper underground for minerals and water
  • Small plants mayalsogrow taller to reach the light, or grow larger leaves ( with abiggersurface area) to take in more sunlight

Competition from its own seedlings:

  • Many plants use the wind to help disperse their seeds- some produce very small, light seeds, easily carried by the wind, some produce fruits with special adaptions for flight e.g. sycamore seeds (shaped like helicopters)
  • Some plants use mini-explosions to help carry their seeds
  • Some take the form of berries, which animals eat, then the seeds are deposited in their waste products
  • Fruits which are sticky also cling to animals, and drop off in other areas later
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Adaptions in Plants

The Transpiration Stream:

  • Plants take up water through their roots
  • It moves up through the plant and is lost through the leaves
  • There are small openings called STOMATA in the leaves of the plant
  • These openings allow gases in and out forphotosynthesisand respiration
  • They also lose water at the same time, due to evaporation

Therateat which a plant loses water is linked to the conditions it is growing in:

  • When it is hot and dry, photosynthesis takes place more quickly, and, as a result, plants lose water more quickly.
  • To stop this, plants reduce their surface area (usually by curling the leaves)
  • or store water in their tissues (in their fleshy leaves, stems or roots, known as succulants).

A big problem for plants is being eaten by animals. here are some adaptions:

  • Vicious thorns
  • Unpleasant tastes
  • Poisonous chemicals
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Questions

1) What three resources do plants compete for?

2) Which of the following adaptions would NOT reduce the arte of transpiration in a plant?

  • A)Fleshysucculant leaves B) Thick waxy cuticles C) Few Stomata D) Reduced leaf area

3) What are the mainproblems for plants living in hotenvironments?

4) Why is competition between animals of the same species so much more fierce than that between different species?

5) State one way in which a plant is adapted to conserve water


6) Why do animals in a cold climate have a thick layer of blubber?


7) An elephant has a small SA:V ratio. How might this affect it in hot climates?

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Answers

1) Water, nutrients and light

2) C)- Few stomata

3) Little water, and few nutrients from the soil

4) Because animals of the

5) Curled leaves- a lower surface area/ storage of water in succulants

6) To provide insulation

7) It may find it difficult to lose heat, but it will also not heat up as quickly as smaller animals

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Questions

1) Name three structures common to plant cells ONLY

2) Where is energy released during aerobic respiration?

3) What is the function of ribosomes?

4) What substance do chloroplasts contain (necessary for photosynthesis)

5) What is the function of the cell wall in plants?

6) How is osmosis like diffusion (NOTE: bonus- haven't actually covered)

7) Why do cells need water?

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Cells

Plant Cells and Animal Cells

Parts in both, and functions:

  • Nucleus- controls the cell's activities
  • Cytoplasm- many chemical reactions take place here
  • Cell Membrane- controls the movement of materials in and out of the cell
  • Mitochondria- where oxygen is used and most of the energy is released during respiration
  • Ribosomes- where protein synthesis takes place- all the proteins needed in the cell are made here

Parts belonging ONLY to plant cells, and functions:

  • Cell Wall- made of cellulose-strengthenscell and gives it support
  • Chloroplasts- found in all green parts of the plant- green because they contain the green substance which gives the plant its colour- absorb light energy to make food for photosynthesis
  • Vacuole- contains cell sap which helps store sugars and salts- keeps the cells rigid and support the palnt
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Chemical reactions in cells

Enzymes

  • Cell chemistry takes place because each one is controlled by an enzyme
  • Each enzyme is a protein which controls the rate of a very specific reaction
  • Makes sure the reaction takes place without becoming mixed up with any other reaction

Found in:

  • Mitochondria- needed for respiration
  • Chloroplasts- needed for photosynthesis
  • Ribosomes- needed for proteinsynthesis
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Specialised Cells

What and Why?

  • cells become specialised in order to carry out particular jobs
  • when a cell becomesspecialised, its structure is adapted to suit the particular job it does
  • specialised cells often look very different to typical plant or animal cells
  • sometimes cells become so specialised they can only carry out one function within the body E.g:
  • sperm
  • eggs
  • red blood cells
  • nerve cells

Organised Cells:

  • Specialised Cells are often grouped together to form a tissue
  • Connective tissues join parts of the body together
  • Nervous tissue carries information around your body and muscles move the body about
  • In many bigger living organisms, several different tissues work together to do different jobs
  • They form an ORGAN
  • Different organs are combined in ORGAN SYSTEMS

CELLA --> TISSUES --> ORGANS --> ORGAN SYSTEMS --> WHOLE BODY

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Answers

1) Cellulose cell wall, Vacuole, Chloroplasts

2) Mitochondria

3) To make proteins

4) Chlorophyll

5) For support and strength

6) Involves the random movement of particles

7) For support and chemical reactions take place in solution

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Specialised Animal Cells

Sperm Cells-

  • Large nucleus (to store genetic information)
  • Contains digestive enzymes to digest through the jelly surrounding egg
  • Containmitochondria(toprovideenergy to swim)
  • Long tail to swim towards the egg

Egg Cell-

  • Large in diameter
  • Contains stored food
  • Large nucleus (to store genetic information)


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Specialised animal cells 2

Fat Cell-

  • Very little normal cytoplasm- leaves room for large amounts of fat
  • Very few mitochondria (use very little energy)
  • Can expand up to 1000 times as it fills with fat

Nerve Cell-

  • Long and thin to carry nerve impulses long distances
  • Form connections with other nerve cells- only in one direction
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Plant Specialised Cells

Palisade Cell-

  • Found in leaf
  • Large surface area
  • Many tightly packed chloroplasts (for photosynthesis)
  • Thin walls so CO2 can diffuse in easily

Guard Cells-

  • Half-circle shape
  • found in pairs on the bottom of a leaf
  • Control theopeningand closing of the stomata


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Plant Specialised Cells 2

Xylem-

  • Hollow because dead- form long tubes totransportwater from roots to leaves
  • Walls contain lignin which is very strong and waterproof

Upper Epidermis-

  • Found on top layer of leaf- closely fitting to provide protection
  • Thin waxy layer prevents water from evaporating from the leaf
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Adaption & Competition in animals

Animals in Hot & Cold climates:

Hot Climates:

  • Thin layer (or no) fur, for little insulation
  • Less fat/blubber, for less insulation
  • Large external features to allow release of heat, as has large surface area
  • Active at night, as it is cooler
  • High surface area : volume ratio, to lose heat more quickly

Cold Climates:

  • Thick layer of fur, for more insulation, and could turn white in winter
  • More fat/blubber for insulation
  • Small external features to keep in as much heat as possible, and avoid release of it
  • Active during the day, as it is warmer
  • Low surface area : volume ratio, to keep heat in
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Surface Area : Volume ratio

  • Important, as it affects the animal's ability to conserve or lose heat
  • The higher the surface area : volume ratio, the faster the rte at which heat can be lost from the body and vice versa
  • Large animals such as polar bearsseemto have a larger surface area : volume ratio than small animals such as mice, but it is not just the total surface area we are concerned with
  • We need to think about how much surface area an animal has inRELATIONto its VOLUME


THEREFORE:

  • Thesmallerthe animal, the higher its surface area : volume ratio
  • Animals often have higher SA:V ratios in hot climates (to lose heat) and lower SA:V in colder climates ( to conserve heat)
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Population Gowth

  • A population is a group of organisms of one species living in acommunity

Population Gowth:

  • At first, populationgrowthis fairly slow, as there are not enough individuals able to breed- this is the LAG PHASE
  • As more individuals mature andbreed, the population beginsto growfasterand faster- this is EXPONENTIAL GROWTH
  • This is the wayallpopulations grow, in IDEAL conditions

However, these phases can be changed-

  • All phases depend on the birth to death rate
  • If the birth to death rate is greater = LAG PHASE
  • If the birth to death rate is much greater = EXPONENTIAL PHASE
  • If the birth to death phase is the same = STATIC PHASE (when the population neither increases nor decreases in size)
  • If the birth to death rate is less than = DEATH PHASE ( when the population begins to decrease rapidly in size)
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