1.1

use a light microscope to examine and identify the structures of a typical plant and animal cell:

diagram of microscope 

when viewing objects start with the lowest power objective lens first to ensure you can locate the object and also prevents damage to the objective lens.

looking at plant cells:

• cut a small piece of onion tissue
• use forceps to peel the inner surface (looks like tissue paper)
• put the onion 'skin' flat on slide and add 2 drops of iodine solution
• gently lower cover-slip onto the slide using a mounted needle
• look at onion cells under the microscope

calculate the actual size of a specimen and calculate magnification using a scale bar:

m > mm x1000                                   μm > mm /1000

mm > μm x1000                                 mm > m /1000

magnification = magnification of eyepeice lens x magnification of objctive lens

triange                                  I = image size

                                              A = actual size

                                              M = magnification

read scale bar = A (actual size)

measure scale bar = I (image size)

know the structure and function of animal cells, to include nucleus and chromosomes, cytoplasm, and cell and nuclear membrane:

animal cell

nucleus - contains chromosomes made up of long lengths of DNA

chromosomes - short lengths of DNA in a chromosome form genes that code for a single characteristic

cytoplasm - chemical reactions occur here

cell membrane - controls movement of substances in and out of cell; is selectively permable (only some substances can pass through)

nuclear membrane - keeps DNA inside the nucleus and protects it from materials in the cytoplasm

know that plant cells have additional structures not found in animal cells: cellulose cell wall, large permanent vacuole and chloroplasts:

plant cell

cell wall - made of cellulose; provides support and protection; fully permeable

large permanent vacuole - stores water and sugars as sap; provides shape and support

chloroplasts - contains chlorophyll to trap sunlight for photosynthesis to make glucose

compare and contrast the structure of bacterial cells with plant and animal cells: non-cellulose cell wall, absence of nucleus and presence of plasmids:

bacterial cell

cell wall - not made of cellulose; provides support and protection; fully permeable

no nucleus - loop of DNA is found loose in the cytoplasm

plasmids - smaller rings of DNA that contain genetic information

understand that multi-celled organisms' cells are organised to form specialised tissues, organs and organ systems to improve exchange with the environment, to transport substances and to communicate between cells:

multi-celled organisms' cells are organised to form;

• specialised tissues
• organs
• organ systems

so they can;

• improve exchange with the environment
• transport substances
• communicate between cells

compare and contrast the patterns of growth and develop in plants and animal cells: animals grow all over and plants grow at apices to produce a branching pattern:

growth = permanent increase in size

animal cells - reproduce to form new cells; this results in growth occuring all over the organism's body gining a rounded shape

plant cell - growth occurs at the tips of roots and shoots; these are called apices; causes plants to grow in a branching pattern

understand that animal cells originate from stem cells which later become specialised and that animal cells lose the ability to differentiate at an early stage of development:

stem cell - a cell that can divide into any type of cell, it is not specialised

animal cells originate from embryo stem cells

during the development of an embryo most of these cells become specialised

can't later change to become a different type of cell - process called cell differentiation

adult stem cells can grow into any type of cell found in the body and are found in organisms at all stages of their lives

adult stem cells have to develop into the types of tissue in which they are found eg. skin, blood and bone marrow stem cells

collection of stem cells

understand: the ethical implications of the applications of stem cell research, the need for government control of this research to protect the public, and the need for validation of this research (for example peer review):

ethics - principals we live by

removing cells from an embryo that could grow into a human, even if that embryo has been produced by IVF and is no longer required is opposed for religious reasons

the embryo is killed and will not develop into a human,embryo has human rights

stem cell research is under strict control in most countries- 

• government control for this research to protect the public
• the need for validation of this research by peer review (review by other researchers working on stem cell research to make sure it works)

investigate the process of diffusion as the movement of molecules from a region of high concentration to a region of low concentration:

body cells need -

• oxygen and glucose (to release energy in respiration)
• amino acids, fats, vitamins and minerals (for healthy growth)

waste materials (need to be removed) - 

• carbon dioxide and water

plants need  - 

• carbon dioxide and water (to make glucose during photosynthesis)

waste materials (need to be removed) - 

• oxygen

diffusion - movement of particles from an area of high concentration to an area of low concentration until they are evenly distributed

animals -

cell respires and uses up oxygen, red blood cells carry oxygen to the body cells. oxyge moves from a high concentration in the blood to a low concentration in the body cells by diffusion

1st diagram

cell respires and makes carbon dioxide. carbon dioxide moves from a high concentraion in the body cells to a low concentration in the blood by diffusion. blood carries carbon dioxide away and this maintains a concentration gradient for movement of carbon dioxide.

2nd diagram

 oxygen diffuses from a high concentration in the alveoli to a low concentration in the blood

carbon dioxide diffuses from a high concentration in the blood to a low concentration in the alveoli

alveolus diagram

palisade mesophyll cells need carbon dioxide for photosynthesis

gaurd cells surround pores called stomata which allow carbon dioxide into the leaf

carbon dioxide moves from a high concentration in the air to a low concentration in the mesophyll cels by diffusion

diffusion in plants