Yr.9 Biology

Yr.9 Biology

Observing Cells
1. Living organisms
  1. All living organisms are made of cells. Cells are the building blocks of life.
  2. Cells are the smallest units found in an organism.
  3. Organisms such as bacteria can be formed from a single cell. Millions of cells can join together to form a person.
  4. Cells are so small that about 100 animal cells would fit across the width of this tiny full stop.
2. Seeing cells
  1. Cells were first seen about 350 years ago.
  2. To see cells you have to look through a microscope.
3. Making observations
  1. To see very small object in detail, you need to use a microscope.
  2. This magnifies the image using lenses. Looking carefully and in detail at an object is called making an observation.
  3. The object you wish to observe needs to be very thin so that light can travel through it. you might need to add coloured die so you can see the object easier.
4. Magnification
  1. The eyepiece lens and objective lens in a microscope have different magnification.
  2. for example, if you have an eyepiece lens of x10 and an objective lens of x20 the object would be magnifies 200 times
Plant and animal cells
1. when you look through a microscope, you will see the have smaller parts inside them. these parts, components, all have an important function. animal cells and plant cells contain some of the same compoonents. however, some parts are different.
  1. Animal cells have an irregular shape. they contain four components - a nucleus, a cell membrane, cyoplasm and many mitochondrion
  2. Plant cells have a more regular structure than animal cells. they contain a nucleus, a cell membrane, cyoplasm and many mitochondrion, like animal cells but they also have a cell wall, a vacuole, and chloroplasts.
2. cytoplasm - this is a 'jelly-like' substance where the chemical reactions in a cell take place.
3. cell membrane - this is a barrier around the cell. it controls what can come in and out of the cell.
4. nucleus - this controls the cell and contains genetic material. Genetic information is needed to make new cells.
5. Mitochondria - this is where respiration happens. Respiration is a reaction that transfers energy for the organism.
6. cell wall - this strengthens the cell and provides support.
7. Vacuole - this contains a watery liquid called cell sap. it keeps the cell firm.
8. Chloroplasts - this is where photosynthesis happens
specialised cells
1. most cells in the human body contain a nucleus, cell membrane, cytoplasm, and mitochondria. However some cells have changes shape and structure so that they can carry out a particular job.
2. Nerve cells carry electrical impulses around your body. they are long and thin and have connections at each end where they can join to other nerve cells around your body
3. Red blood cells
  1. Red blood cells transport oxygen around the body
  2. they contain haemoglobin, a red pigment that joins to oxygen
  3. unlike most animal cells they have no nucleus
  4. they have a different shape, this increases their surface area for carrying oxygen.
4. sperm cells
  1. sperm cells carry male genetic material.
  2. they have a streamlined head and a long tail. this allows it to move through liquid.
  3. they contain lots of mitochondria to transfer energy
5. Leaf cells
  1. a cell from the top of a leaf. its scientific name is a palisade cell.
  2. The cells at the top of the leaf carry out photosynthesis.
  3. The cells are long and thin and packed with chloroplasts. this means they have a large surface area for absorbing energy transferred from the sun
unicellular
1. a unicellular organism is an organism that is made up of just one cell.
2. Amoeba
  1. an amoeba is a unicellular organism that has no fixed shape, it just looks like a blob of jelly.
  2. they can be found in fresh water,salt water, wet soil and even inside animals.
  3. an amoeba consists of a cell membrane filled with cytoplasm. inside the cell there is also a nucleus, which controls growth and reproduction
3. an euglena is a microscopic organism, found in fresh water. it is like a Amoeba but it contains a cytoplasm and a nucleus and also they have chlorolasts.

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