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Cells make up tissues, organs and systems
·Cells grouped- tissue; working together- Organ
·Group of Organs- System
·Organ Systems make up a full Organism
·Most cells for their specific function:
·Palisade Leaf Cells are adapted for Photosynthesis:
Packed with Chloroplast
Tall/surface area- Absorbing CO2
Thin shape: pack loads of them at top of a leaf
·Guard cells are adapted to open and close Pores:
Special kidney shape to open and close
sensitive to light and close at night to save water
·Red blood Cells are adapted to carry oxygen:
big surface area for absorbing oxygen
Packed with haemoglobin-absorb oxygen
No nucleus: more room
Biology 2 (i)…read more

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Diffusion: gradual movement of particles.
·Diffusion is the passive movement of particles from an area of
HIGH CONCENTRATION to an area of LOW CONCENTRATION
·Diffusion happens in both liquids and gases
·Only very small molecules can diffuse through cell membranes ­
Glucose, Amino acids, Water and Oxygen. Big Molecules- Starch
and proteins cannot diffuse.
Osmosis:
·Special case of diffusion
·Osmosis is the movement of water molecules across a partially
permeable membrane from a region of high water concentration to
a region of low concentration
·Water moves in and out of cells by osmosis/Pass both ways.
·Tissue Fluid- Water, oxygen and glucose-surrounds the cells/
different concentration to fluid inside cell.
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Photosynthesis: SUNLIGHT
Carbon Dioxide + Water chlorophyll Glucose + Oxygen
·Photosynthesis produces glucose using sunlight:
·Food in Plants- Glucose
·Happens in the leaves- green plants
·Happens inside the chloroplasts- chlorophyll absorbs sunlight- convert into co2
water and glucose. Oxygen is also produced
4 things needed for photosynthesis:
·Light- sun
·Chlorophyll- found in chloroplasts/ Absorbs energy
·Carbon dioxide- enters leaf from air
·Water- comes from the soil/ up the roots and steam into leaf
Rate of photosynthesis is affected by light, amount of co2 and the temperature.
·Night- light is limiting factor
·Winter- Temperature is limiting factor
·Warm enough- Co2 limiting factor
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How plants use the glucose
·Respiration- glucose used for respiration
·Fruits- Glucose + fructose= Sucrose for storing in fruits
·Cell walls- converted into cellulose
·Proteins- glucose combined with nitrates= Amino acids ­ proteins
·Seeds- Turns into lipids for storing in seeds
·Starch- glucose turned into starch and stored in the roots? Ready for use
when photosynthesis isn't happening like in the winter.
Minerals-
Plants need minerals in order to grow properly
Nitrates- Amino acids- proteins
Magnesium- needed to make chlorophyll- needed for photosynthesis
Lack of these nutrients causes deficiency
Lack of nitrates- plants starts to show stunted growth.
Lack of Magnesium- leaves of the plant start to turn yellow/ lack of chlorophyll
Mono culture can cause deficiency as the soil becomes dificient in the minerals
which the crop uses a lot.
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Pyramids of Number and Biomass
There's less energy and biomass every time you move up a stage(trophic
level) in a food chain Fleas
^not always true. E.g-
Fox
Rabbits
Dandelions
Energy disappears somehow:
·Energy from the sun is the source of nearly all life on earth
·Respiration and movement supplies power for all life processes- most of the
energy is lost to the surroundings as heat
·Some of the material which makes up plants and animals is inedible/ bones
etc- doesn't pass to the next stage- energy lost.(excretion)
Elements are cycled back to the start of the food chain by decay:
·Returned by waste products/ when organisms die- broken down digested by
micro-organisms- back in soil.
·Microorganism work best in warm moist conditions- plenty of oxygen also.
·Important elements are recycled
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