Cell Biology

Question 1

Prokaryotic- smaller and simpler, e.g. bacteria.

Prokaryote- a prokaryotic cell, single called organism.

Answer 1

Eukaryotic- complex, include all animal and plant cells.

Eukaryotes- organisms made up of eukaryotic cells.

Question 2

ANIMAL CELLS

Nucleus- genetic material, controls cell activity.

Cytoplasm- gel-like, most chemical reactions occur, contains enzymes that control chemical reactions.

Cell Membrane- holds together, controls what goes in and out.

Mitochondria- most reactions for aerobic respiration.

Ribosomes- where proteins are made in the cell.

Answer 2

PLANT CELLS
Everything animal cells have plus:

Cell Wall- made of cellulose, supports and strengthens cell.

Permanent Vacuole- contains cell sap, weak solution of sugar and salts.

Chloroplasts- photosynthesis occurs, makes food for plant, green substance- chlorophyll, absorbs like for photosynthesis.

Question 3

-Differentiate to become specialised.

-Differentiation- cell changes to
become specialised.

• Develop different sub cellular structures- turn into different types of cells- allows to carry out specific functions.
• Undifferentiated cells- stem cells.

Answer 3

EXAMPLES:

Sperm Cells-

• Specialised for reproduction.
• Long tail.
• Streamline head.
• Helps swim to egg.
• Lot of mitochondria provide energy.
• Carries enzymes to digest through cell membrane.

Question 4

Nerve Cells-

• Specialised for rapid signalling.
• Carry electrical signals.
• Long, branched connections to form network.

Answer 4

Muscle Cells-

• Specialised for contraction.
• Contract quickly.
• Long.
• Lot of mitochondria to generate energy.

Question 5

Root Hair Cells-

• Specialised for absorbing water and minerals.
• Big surface area for absorbing water and mineral ions from soil.

Answer 5

Phloem and Xylem Cells-

• Specialised for transporting substances.
• Transport food and water round plant.
• Joined end to end to for tube.
• Hollow, few sub cellular structures so stuff can flow.

Question 6

MICROSCOPY

Light Microscopes-

• Use light and lenses
• Let us see individual and large sub cellular cells.

Electron Microscopes-

• Use electrons.
• Much higher magnification, see smaller things in more detail.

Answer 6

FORMULA

Magnification = Image Size / Real Size

Image Size = Magnification x Real Size

Real Size = Image Size / Magnification

Question 7

CELL CYCLE

GROWTH & DNA REPLICATION

• Cell not diving.
• DNA spread out in long strings.
• Grow and increase amount of sub cellular structures.
• Duplicates DNA, copied and forms X-shaped chromosomes- each arm is exact duplicate.

Answer 7

MITOSIS

• Cell fibres pull arms apart.
• Arms go to opposite ends of the cell.
• Membranes ford around the new sets of chromosomes to form two new cells.
• Two new daughter cells, identical.

Question 8

STEM CELLS
Undifferentiated cells

• Divide to produce more.
• They can differentiate.
• Potential to be any type of cell at all.
• Some can be grown in a lab to produce clones.

Answer 8

DIFFUSION

• Gradual movement of particles from high to low concentration.
• Bugger difference in concentration, faster diffusion rate.
• Higher temperature, faster diffusion rate.
• Occurs through cell membrane.

Question 9

OSMOSIS

• Movement of water molecules across a partially permeable membrane from high to low water concentration.
• Partially permeable membrane is just one with small holes.
• Acts as if it is trying to even up.
• Type of diffusion.

Answer 9

ACTIVE TRANSPORT

• Absorbed against the concentration gradient, low to high.
• Root hair cells, concentration of minerals is higher in the cell so can’t use diffusion.
• Allows the plant to absorb minerals from a dilute solution.