B1- Cell Biology

Cell Differentiation

Process by which cell changes to become specialised for its job; New subcellular structures are created

Sperm cells and how they are specialised

Specialised for reproduction,

\-carriers of male DNA.

\-They are specialised with their long tail and streamlined head

Nerve Cells and how they are specialised

Specialised for Rapid signalling,

\- carry electrical signals from one part of the body to another.

\-long axon which carrises impulses insulated by myelin which speeds up transmission

\-dendrites increase surface area so other nerves can connect more easily

\-synapses are junctions which allow impulses to pass from one nerve cell to another

Muscle Cells + Specialisation

Specialised for Quick Contraction,

\-Long ( for space to contract) and contain lots of mitochondria to generate energy for contractions.

Root Hair Cells + Specialisation

Specialised for absorbing Water and Minerals,

\-on the surface of plants and roots, long which gives them a big surface area for absorbing water and minerals

\-No chloroplast as underground

Muscle cells

Can contract (get shorter) as they contain protein fibres

\-slide over the top of each other

\-contain lots of mitochondria

Phloem and Xylem + Specialisation

Specialised for transporting substances

Xylem- Water and minerals (Transpiration) - Are hollow no subcellular structures thick walls lignin

Phloem- Food (Translocation)- Have few subcellular substances so things can flow through. Small pores (sieve plates) in walls to allow sap through

How many chromosomes do humans have

23 pairs

Cell cycle

Organisms divide to produce new cells as part of the cell cycle

Mitosis

Used for growth and repair (replacing damaged cells)

Stem cells

Unspecialised cells which can be useful when instructed what to become and can be harvested from embryos or bone marrow

Where are stem cells found in plants

Meristems ( used to make full identical copies of plants cheaply)

Diffusion

Concentration of particles from a high to low concentration

Osmosis

Concentration of water molecules going from a high to low concentration after passing through a partially permeable membrane

chopped potato slice in a sugar solution

Practical for osmosis

Active transport

The concentration of a substance going up the concentration gradient from low to high

What specialised cell utilises active transport to absorb minerals and water

Root hair cell

Where does gas exchange take place in the lungs

The alveoli with their large surface area and thin walls

What is the villi

Lining in the small intestine helping digested food be absorbed quicker

with a large surface area and blood flow

What diffuses into the stomata on the bottom of a leaf

C02

What diffuses out of the leaf

Oxygen and water vapour ( due to the low water concentration outside)

What controls the size of the stomata?

Guard cells which close the stoma if the plant is losing more water than it is gaining.

What specialisation do gills have

Large surface area to allow gas exchange

What is a chromosome

Genetic material