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biology (building blocks of life (plant cells (vacuole, cell membrane,…
biology
building blocks of life
the first microscope
Zacharias janssen (1585-1632) was a dutch spectacle maker. around 1590 he was experimenting with lenses and placed 2 lenses inside a tube. when he looked through the tube, objects appeared much larger than when he had used a single lens. he had created the first true microscope.
antonic van leewenhoek (1632-1723) was an expert microscope builder. he built microscopes that were able to magnify up to x250
cell theory
in 1833, Scottish botanist Robert brown (1773-1858) discovered that plant cells were not just empty boxes and that they had even smaller structures inside them. the first structure identified was the nucleus. it took another 70 years to identify other structures like chloroplasts.
in 1838, german scientist Matthias schleiden (1804-1858) analysed the known information about plant cells. he proposed the idea that cells are the basic building blocks of all plants, that new plants start off as a single cell and as plants grow, new cells are produced.
a year later in 1839, theodor schwann (1810-1882) proposed that animals are also made of cells. this meant that cells are the basic unit of life for both plants and animals. identifying this link is one of the most renowned scientific discoveries.
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cell reproduction
cells need to reproduce for a number of reasons e.g. repair, growth, regeneration
the type of cell reproduction that is involved with growth, repair and replacement is called MITOSIS.
mitosis is the orderly division of one cell (the parent cell) in two cells (the daughter cell). each daughter cell has the same type and amount of material as the parent cell.
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specialised cells
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specialised animal cells
animals are complex multicellular organisms with a large number of different cell types. the human body contains about 50 trillion cells.
muscle cells
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all voluntary and involuntary muscles contain a large number of mitochondria. this is because 3 muscles require a lot of energy to keep working and it is the mitochondria that provide the energy.
nerve cells
nerve cells make up your brain. they also carry information from your brain to other parts of your body such as your muscles, and from your muscles back to your brain.
blood cells
red blood cells carry oxygen from your lungs around your body to the cells, where it is used to release the energy you need. they also carry some of the waste carbon dioxide from your cells back to your lungs so that you can get rid of it from your body.
the white blood cells have a very different job. they are part of the immune system and help the body to fight infection.
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specialised plant cells
like animals, plants are multicellular organisms. plants have specialised cells of different shapes and sizes, but they do not have as many different cells as animals. Each type of cell is specialised to carry out a different function within the plant.
making things bigger
microscopes
very small things need to be magnified or made bigger so that they become visible to us. scientists use microscopes to do this. objects that can only be seen using a microscope are described as microscopic.
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a monocular microscope only has one eyepiece (or ocular lens). microscopes with 2 eye pieces (or ocular lens) are called binocular microscopes.
stereo microscopes
using a stereo microscope is like having 2 monocular microscopes joined together, with each one focusing on the same point but from different angles. the image you see is in 3 dimensions. you move the object to the right, the image moves to the right.
magnification
the magnification of the microscope tells you how much bigger the image is than the real object. if the microscope has a magnification of x10, the image is 10 times bigger than the actual object. the symbol x stands for magnified by.
very small measurements
many of the objects observed using a microscope are much smaller than a millimetre and so they must be measured in units smaller than a millimetre.
a micrometre is one-thousandth of a millimetre, or one-millionth of a metre. a micrometre is the unit most often used by scientists to measure microscopic objects.
electron microscope
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electron microscopes use beams of tiny particles called electrons instead of light, and are able to magnify up to a million times.
there are 2 types of electron microscopes; transmition electron microscopes (TEM) and scanning electron microscopes (SEM)
cell to organism
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organs
tissues are grouped together to make organs. all the different tissues contribute to the job that the organ has to do. there are many different organs in your body, such as liver, kidneys, and heart. even your skin in=s an organ and it is the largest organ in the body!
organ systems
the organs in your body do not work independently. organs are organised so that they can work together to complete a task. these organs form an organ system.
plant tissues and organs
plants have fewer organs and organ systems than animals. plants are mainly organised by the tissue level and have very few organs. these tissues and organs allow the plant to carry out essential functions such as photosynthesis, transport, and reproduction.
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plant organs
the main organs of a plant are its roots, stems, and leaves. these organs work together to bring together the raw materials required for photosynthesis. photosynthesis is the process in which the plant makes glucose plants use the energy from glucose for their life processes; without it they could not survive..