Additional Science Biology

Covers the additional science biology units with text and pictures.

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  • Created by: Cam Ward
  • Created on: 05-04-11 16:51

Cells.

Animal cells and plant cells have features in common, such as a NUCLEUS, CYTOPLASM, CELL MEMBRANE, MITOCHONDRIA AND RIBOSOMES.

Plant cells also have a CELL WALL and often have CHLOROPLASTS and a PERMANENT VACUOLE.

DISSOLVED SUBSTANCES PASS INTO AND OUT OF CELLS BY DIFFUSION.

WATER PASSES INTO AND OUT OF CELLS BY OSMOSIS.

DIFFUSION OCCURS WHEN PARTICLES SPREAD. PARTICLES MOVE FROM HIGH CONCENTRATION TO LOW CONCENTRATION.

OSMOSIS is the movement of water from a LESS CONCENTRATED solution to a MORE CONCENTRATED solution through a PARTIALLY PERMEABLE MEMBRANE.

PLANTS GAIN WATER THROUGH OSMOSIS.

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Plant cell and animal cell diagram.

both cells have a membrane on the outside, and cytoplasm and a nucleus inside. In the plant only are the cell wall, vacuole, and chloroplast.  (http://www.bbc.co.uk/schools/gcsebitesize/science/images/aqaaddsci_06.gif)

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Photosynthesis.

Green plants ABSORB LIGHT ENERGY  using CHLOROPHYLL in their leaves.

They use it to REACT CARBON DIOXIDE WITH WATER to make a sugar called GLUCOSE.

The GLUCOSE is used in RESPIRATION, OR CONVERTED INTO STARCH AND STORED. OXYGEN IS PRODUCED AS A BY-PRODUCT.

This is called PHOTOSYNTHESIS. The factors that can limit this are TEMPERATURE, CARBON DIOXIDE AND LIGHT INTENSITY.

Plants also need MINERAL IONS, including NITRATE and MAGNESIUM.

NITRATE - USED FOR MAKING AMINO ACIDS WHICH ARE NEEDED TO MAKE PROTEINS. DEFICIENCY WILL CAUSE STUNTED GROWTH.

MAGNESIUM - USED FOR MAKING CHLOROPHYLL. DEFICIENCY WILL CAUSE LEAVES TO TURN YELLOW.

CARBON DIOXIDE + WATER AND LIGHT ENERGY MAKES GLUCOSE +OXYGEN.

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Leaf cell diagram.

the cell includes: a waxt outer cuticle, the upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, stoma, and guard cells with chloroplasts  (http://www.bbc.co.uk/schools/gcsebitesize/science/images/bi05004.gif)

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Energy Flows.

The amount of MATERIAL and ENERGY DECREASES from one stage of the food chain to the next.

Energy released by RESPIRATION used for MOVEMENT and other life processes, and is eventually LOST AS HEAT to the surroundings.

Energy is LOST in WASTE MATERIALS.

CARBON DIOXIDE is REMOVED from the atmosphere by PHOTOSYNTHESIS.

ORGANISMS RETURN CARBON DIOXIDE to the environment by RESPIRATION.

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Pyramid of biomass diagram.

(http://www.bbc.co.uk/schools/gcsebitesize/science/images/23_2_pyramids_of_biomass_2.gif)

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Enzymes.

ENZYMES are BIOLOGICAL CATALYSTS. There are optimum TEMPERATURES and PH VALUES at which their ACTIVITY IS GREATEST.

ENZYMES are also PROTEINS, and are usually DENATURED ABOVE ABOUT 45 degrees celsius.

ENZYMES are important in RESPIRATION.

AEROBIC RESPIRATION RELEASES ENERGY FROM GLUCOSE.

The equation for  AREOBIC RESPIRATION is:

GLUCOSE + OXYGEN MAKES CARBON DIOXIDE + WATER (+ENERGY).

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Enzymes and digestion.

ENZYMES are IMPORTANT in DIGESTION.

ENZYMES ARE USED in the manufacture of FOOD AND DRINK.

AMYLASE BREAKDOWN STARCH TO SUGARS.

PROTEASES BREAKDOWN PROTEINS TO AMINO ACIDS.

LIPASES BREAKDOWN LIPIDS TO FATTY ACIDS + GLYCEROL.

AMYLASE PRODUCED IN THE SALIVARY GLANDS, PANCREAS, SMALL INTESTINE.

PROTEASE PRODUCED IN THE STOMACH. PANCREAS, SMALL INSTESTINE.

LIPASE PRODUCED IN THE PANCREAS AND SMALL INTESTINE.

HUMAN ENZYMES WORK BEST AT 37 DEGREES CELSIUS.

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Homeostasis.

The TEMPERATURE within the body must be kept at a near CONSTANT TEMPERATURE, this is HOMEOSTASIS.

These conditions include WATER CONTENT, ION CONTENT, BODY TEMPERATURE AND BLOOD GLUCOSE CONCENTRATION.

The THERMOREGULATORY CENTRE is the part of the brain that monitors and CONTROLS BODY TEMPERATURE.

The PANCREAS monitors and controls BLOOD GLUCOSE CONCENTRATION. It produces a hormone called  INSULIN that REDUCES BLOOD GLUCOSE LEVELS.

DIABETES IS A DISEASE THAT CAN BE CAUSED BY INSUFFICIENT INSULIN.

 

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Cell division.

CHROMOSOMES are made from DNA. GENES are short sections of DNA.

Genetically identical cells are produced by a type of cell division called MITOSIS.

GAMETES are produced by a type of cell division called MEIOSIS.

GAMETES CONTAIN A SINGLE SET OF CHROMOSOMES.

BODY CELLS CONTAIN TWO SETS OF CHROMOSOMES.

MITOSIS - TWO NEW CELLS FORM.

In MALES, the two sex chromosomes are DIFFERENT. They are XY.

In FEMALES, the two sex chromosomes are the SAME. They are XX.

The main features of MEIOSIS are that the CHROMOSOMES ARE COPIED and that the CELL DIVIDES TWICE, FORMING FOUR GAMETES.

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Stages of meiosis diagram.

chromosomes divide, similar chromosomes pair up, sections of DNA get swapped, pairs of chromosomes divide, chromosomes divide  (http://www.bbc.co.uk/schools/gcsebitesize/science/images/aqaaddsci_13.gif)

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Inheritance.

ALLELES are DIFFERENT FORMS OF A GENE. They can be DOMINANT OR RECESSIVE.

HUNTINGTONS DISEASE is a disorder of the nervous system that is CAUSED BY A DOMINANT ALLELE.

CYSTIC FIBROSIS is a disorder of the cell membranes CAUSED BY A RECESSIVE ALLELE.

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Genetic diagrams showing the outcome of Mendela.

Genetic diagram of FF x ff for flower colours (http://www.bbc.co.uk/schools/gcsebitesize/science/images/aqaaddsci_14.gif) 

All the offspring have red flowers, even though they carry the recessive allele for white flowers

In genetic diagrams, the dominant allele is shown as a capital letter, while the recessive allele is shown as a lower-case letter.

Genetic diagram of Ff x Ff for flower colours (http://www.bbc.co.uk/schools/gcsebitesize/science/images/aqaaddsci_15.gif)

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Comments

arsalan hassan

Thankyou for sharing

Ria

Cool :) Thanks :)

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