Biology 12 Cells and the environment

Cells exchange matter and energy In: Out:

Cells exchange matter and energy In: Oxygen Nutrients eg glucose (carbon dioxide and light energy in plants) Water Ions Out: Carbon dioxide Wastes eg urea (oxygen in plants) Water Ions Heat energy Processes: Respiration Synthesis Growth Division Photosynthesis (in plants)

Responding to the environment Internal environment = cell cytoplasm External environment – Unicellular organisms Multicellular organisms

Responding to the environment Internal environment = cell cytoplasm External environment – Unicellular organisms Multicellular organisms Outside worldblood, intercellular fluid

Unicellular responses to the environment 1 Engelmann’s experiment

Unicellular responses to the environment 1 Engelmann’s experiment Light split by lens Alga growing under split light – produce less oxygen under green light Bacteria move to where there is more oxygen

Unicellular responses to the environment 2 NaCl concentration (M)Number of contractions/min

Unicellular responses to the environment 2 NaCl concentration (M)Number of contractions/min Contractile vacuole changes activity depending on salt concentration

Unicellular responses to the environment 3 Euglena Eyespot detects light Flagellum moves organism toward slight or food Contractile vacuole changes activity depending on salt concentration

Surface area and volume Calculate the volume and surface area for these:

Surface area and volume Calculate the volume and surface area for these: 1 cubic unit 6 square units 8 cubic units 24 square units

Does size matter? As size increases: What happens to volume? What happens to surface area? What happens to surface area to volume ratio?

Does size matter? As size increases: What happens to volume? What happens to surface area? What happens to surface area to volume ratio? decreases increases

Surface area and volume 2 Size1x1x12x2x23x3x34x4x4 Surface area Volume SA: Vol Size of sides Surface area volume SA:Vol

Surface area and volume 2 Size1x1x12x2x23x3x34x4x4 Surface area Volume SA: Vol6:13:12:11.5:1 Size of sides Surface area volume SA:Vol

Affect of shape on surface area and volume Calculate the volume and surface area for these: 2x 2x2 1x1x8 4x2x1

Affect of shape on surface area and volume Calculate the volume and surface area for these: 2x 2x2 1x1x8 4x2x1 8 cubic units 24 square units 28 square units 34 square units

Potato experiment Starting the experiment:

Potato experiment 2 What hypothesis is being tested? What was the control? What was the independent variable? What was the dependent variable What variables were controlled? Predict the results you will see.

Potato experiment 2 What hypothesis is being tested? What was the control? What was the independent variable? What was the dependent variable What variables were controlled? Predict the results you will see. Size or shape will affect the absorption of iodine Smallest cube in water Size & shape of potato Amount of mass gained Colour change

Results of potato experiment What can be seen? What does this indicate?

Results of potato experiment What can be seen? – potatoes have turned black where iodine has entered. What does this indicate? More iodine has entered the smaller & flatter shaped ones. Larger shapes have less surface area for exchange & so iodine hasn’t reached their centres

Exchange of material Occurs at the cell membrane Involves the processes of diffusion, osmosis and active transport Occurs slowly

How cells increase their surface area Size Shape Folding Cell extensions pseudopods microvilli

Determining the components of the cell membrane Beetroot lab – part A acid base waterDistilled water detergent

Beetroot experiment part A What hypothesis is being tested? What is the control? What is the independent variable? What is the dependent variable What variables are controlled? How will this tell you about the components of the cell membrane?

Size of objects under the microscope 1 Magnification x100, field of view 1500  m

Size of objects under the microscope 1 Magnification x100, field of view 1500  m ~ 500  m

Size of objects under the microscope 2 Magnification x400, field of view for x100 = 1600  m

Size of objects under the microscope 2 Magnification x400, field of view for x100 = 1600  m Field of view for x400 = 400  m Size = 400  m

Magnification and field of view -review 1 magnification x 40 magnification x 400 field of view 4000  m field of view  m Magnification has by a factor of Field of view has by a factor of

Magnification and field of view - review 2 magnification x 100 magnification x 400 field of view  m field of view 400  m Magnification has by a factor of Field of view has by a factor of

Label the cell

Cell membraneMitochondrion Golgi body Vacuole Smooth endoplasmic reticulum Ribosomes Rough endoplasmic reticulum Cytoplasm Nucleus Nucleolus Chromatin/DNA