biology part one

Animal cells

nucleus:controls all the activities of the cells and hold the information for new cells and organisms

• cell membrane:controls what goes in and out of the cell
• cytoplasm:is where all the chemical reactions take place
• mitochondria:where mosy energy is released for respiration
• ribosomes: protein synthesis occurs

Plant cells

has all the things an animal cell has and these 3 more things

• cell wall: made of cellulose and strengthens the cell
• chloroplast: contains chlorophyl for photosynthesis
• permananent vacuole: contains cell sap so the the cell is rigid and adds support
  

some cells are specials so they can carry out a particular job

• root hair cells have tiny hair like structures which increase the surface area of the cell
• ovum(egg cell) is a large cell that has a massive food reserve for the developing embryo
• sperm cell has a tail so it can move
• xylem is long thing and hollow and is used to transport water from the stem and root
• palisade cell is pack with chloroplast
• nerve cell have long slender axons thats can carry nerve impulses
• white blood cell can change shape in order to engulf and destroy invading organisms
• red blood cells is packed full of haemoglobin

chemical reactions inside cells are controled my enzymes

you can find enzymes in the cytoplasm and mitchondria

cells have to constantly

• replace used up substances eg.food and oxygen

• remove substances like carbon dioxide and other waste products

diffusion is the spreading of particles of gas or any substance in solution through a net movement from a region of high concentration to a region of low concentratio.diffusion doesnt require energy

the greater the difference in concentration the faster the rate of diffusion

osmosis is the movement of water through a partially permable membrane from a dilute solution (high concentration) to an area of low concentration

active transport is the spreading of particles of gas or any substances in solution through a net movement from a region of low concentration to a region of high concentration

it uses energy !

photosynthesis occur in green plants that are exposed to light. light energy is absorbed by chlorophyll found in the chloroplasts in some plant cells. light energy is used to convert carbon dioxide and water into glucose

four things needed for photosynthesis

• carbon dioxide from air
• water from soil
• light from the sun
• chlorophyl in leaves

carbon dioxide + water ( light and chlorophyll ) oxygen + glucose

the products of photosynthesis is oxygen and glucose

the glucose can be used to provide energy for respiration

concerted to insouluable starch which is stored in stem leaves or roots

light- is there is little or no light photosyntheis cannot take place regardless of if co2 and temp levels are alright. as light intensity increases so does the rate of photosynthesis

temp : as plants are living things its controlled by enzymes and if the temp raises past 40-50 degrees then the enzymes will become denatured and the rate of photosynthesis will fall

carbon dioxide. there is only 0.04% co2 in the atmopshere so co2 is often the limitiing factor . most of co2 is used up in respiration

as co2 concentration inceases so does the rate of photosynthesis

greenhouses can control the rate of photosynthesis plants will grow more quickly and become bigger and stronger

• radiation form the sun is the source of all energy for all communities of living organisms
• photosynthesis captures a small fraction of solar energy which reaches them
• the energy is stored in substances which make up the cells of the plant.
• passed onto organisms which eat the plant-this transfer of enrgy would be represented ina food chain

grass - rabbit - stoat - fox (rabbit eats grass, stoat eat rabbit, fox eats stoat)

Producers Green plants - they make food by photosynthesis. Primary consumers Usually eat plant material - they are herbivores. For example rabbits, caterpillars, cows and sheep. Secondary consumers Usually eat animal material - they are carnivores. For example cats, dogs and lions. Predators Kill for food. They are either secondary or tertiary consumers Prey The animals that predators feed on. Scavengers Feed on dead animals. For example, crows, vultures and hyenas are scavengers. Decomposers Feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces.

biomass is the mass of living materials in a food chain the biomass at each stage gets less than it was at its previous stage

biomass and energy are loss at every stage due to

• materials and energy beign lost in faeces(waste)
• energy realesed through repiration being lost in movement and heat

A pyrimid of biomass is a chart, drawn to scale, showing the biomass at each stage in a food chain. The bars become narrower as you reach the top. This pyramid of biomass is for the food chain:

grass - rabbit - stoat - fox

the energy and biomass is passed on when and animal eats another . the fox would get the last bit of energy (which wouldnt be alot)

the loss of energy is mainly due to heat loss watse and movement .the effiencancy of food production can be improved by

• reducing the number of stages in food chain
• limiting animals movement
• controling animals temp

• co2 removed from atmosphere by green plants for photosynthesis. some co2 is returned by respiration
• the carbon obtained by photosynthesis is ised by plants to make carbohydrates fats and proteins .
• plants are eaten by animals some carbon becomes fats and proteins in animals
• animals respire relaesin co2 into atmosphere
• plants and animals die. othere animals and microorganism feed on there bodies causing them to decompose
• detrious feeders and microorganisms respire releasing co2 into the atmosphere

living things remove materials from the enviroment for growth and other processes

when the organisms die or excrete waste the materials are returned to the enviroment

microorganisms break down waste and dead bodies . this decay process releases substances needed by plants for growth

mircoorganisms digest materials faster in conditions that are warm moist and have plenty of oxygen

microorangisms are used in sewage works to break down human waste and in compost heaps to break down plant material.