This document is a condensed summary of the entire CGP book for GCSE AQA Biology. In writing these notes, I achieved a 9 (A**) grade, and I hope you will reap the same reward from using these as I did.
,Eukaryotic cells
Animal and plant cells are eukaryotic cells.
u ⑧
i
-
....
2
cell membrane
&
plant cells usually have the same subcellular structures as animal cells ,
along with a few others.
nucleus contains genetic information of the cell and controls its
:
activity
.
cell membrane :
controls what diffuses in and out of the cell and maintains its structure
.
Mitochondria Aerobic respiration occurs:
here for
energy release .
cytoplasm
:
most chemical reactions occur here
ribosomes where protein synthesis occurs
:
.
cell wall made of cellulose supports and strengthens the cell .
:
,
vacuole stores cell sap (weah solution of sugars and salts).
:
Chlorophyll green pigment that absorbs light for photosynthesis
:
a .
Bacterial cells
meta
Bacterial cells are prokaryotes.
They do not have a true nucleus chloroplasts or mitochondria
. ,
They have a single strand of DNA that floats freely in the
cytoplasm
.
Mey also contain small rings of DNA called plasmids.
, magnification -
image size
real size
Light microscope : uses light and lenses to form an image of a specimen and magnify it to allow us to see
individual cells and large subcellular structures
Electron Microscope :
uses electrons to form an image and has a much higher magnification than light microscopes
How to prepare a slide leg :
Onion cells) :
Add a drop of water to the centre of a clean slide .
2 Cut up an onion and separate it into layers then use tweezers to peel off some epidermal tissue from one of the layers .
-⑭-- lenses
3
Using
/
the tweezers place the epidermal tissue into the water on the slide .
--
-
,
/
- -
↑
Add a drop of iodine solution to stain the cell to highlight the separate structures in the cell .
S
5
Place a cover slip over it , avoiding air bubbles that will obstruct the view of the specimen .
-
-
-
fine and stage
G
Clip the prepared slide onto the stage. course
adjustment light source
7
Select the lowest powered objective lens .
knobs
·
use the coarse adjustment knob to move the stage until the image is roughly in focus .
·
Adjust the focus further with the fine adjustment Knob until there is a clear image of the slide .
10
If a view of the slide in greater magnification is needed use a higher powered objective lens and refocus accordingly .
,
, the digestive system
·
The main nutrients are
carbohydrates
:
liver
rectum
H
anus
oesophagus
: proteins
lipids
These molecules are too big to be absorbed into the bloodstream so
, ,
they have to be .
digested
Digestionis the process in which large food molecules by enzymes to be absorbed into the
bloodstream .
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