B1: Cell Biology

What are the 2 types of cell?

Eukaryotic and Prokaryotic

T or F: animal and plant cells and prokaryotic

F - animal and plant cells are eukaryotic

Define subcellular structures?

Different parts of a cell

What is the role of the nucleus?

Controls the cell and contains genetic material

What is the role of the mitochondria?

The site of aerobic respiration in cells and where energy is released from respiration

What is the cytoplasm?

A jelly-like substance where most of the cells chemical reactions happen.

What does the cytoplasm contain to help it control the chemical reactions?

Enzymes

What is the role of the cell membrane

Controls what enters and leaves the cell

What is the role of ribosomes?

Where proteins are made in the cell

T or F: plant cells contain all of the subcellular structures in an animal cell?

T

What is the role of the cell wall?

Provide structure and support to the cell

What is the cell wall made out of?

Cellulose

What is the role of the permanent vacuole?

Stores cell sap

What is the role of the chloroplasts?

Where photosynthesis occurs

What is the name of the pigment that chloroplasts contain?

Chlorophyll

What colours of light does chlorophyll absorb?

Red and blue

What is the role of chlorophyll?

Absorb light energy for photosynthesis

What type of cells are bacteria cells?

Prokaryotic

T or F: Prokaryotic cells do not contain a true nucleus?

T

How do prokaryotic cells store genetic material?

As a circular strand in the cytoplasm

Define plasmids

Small rings of DNA found in prokaryotic cells

What 2 subcellular structures are found in eukraryotic cells but not prokaryotic cells?

Chloroplasts and mitochondria

Why do we use microscopes?

To allow us to see things we cannot see with the naked eye

What are the 2 types of microscope?

Light and Electron

Which type of microscope has a higher magnification and higher resolution?

Electron

What is the formula to calculate magnification?

Magnification = image size / actual size

Define magnification.

How many times larger an object is compared to the real thing

Define resolution

The ability to distinguish between 2 points in an image

What is a microscope slide?

A small piece of glass or plastic which the specimen is placed on

What solution can be used as a stain on microscope specimens?

Iodine

What is the part of the microscope called that you look through?

Eyepiece lens

What is the part of the microscope onto which the slide is placed?

Stage

What is the name of the lenses used to change the magnification of the specimen?

Objective lenses

How can you change the height of the stage on a light microscope?

Turn the coarse focus wheel

How can you adjust the focus of the image on a light microscope?

Turn the fine focus wheel

Define differentiation.

The process by which a cell develops different subcellular structures to become specialised for a specific function

T or F: plants retain the ability to differentiate throughout their life?

T

What are unspecialised cells called?

Stem cells

What is cell specialisation used for in mature animals?

Repairing and replacing cells

What is the function of a sperm cell?

To fertilise an egg cell

Why does a sperm have a long tail and a streamlined head?

To help it swim towards the egg

Why do sperm cells have lots of mitochondria?

To provide it with extra energy needed to swim to the egg and fertilise it

What do sperm cells carry in their heads?

Enzymes

What is the function of a nerve cell?

Carry electrical signals around the body

What are the branched connection on the ends of nerve cells called?

Dendrites

What is the function of a muscle cell?

Contract and relax to provide movement

Why are muscle cells long?

So they have space to contract

Why do muscle cells contain lots of mitochondria?

To generate the energy needed for contraction

What are root hair cells specialised to do?

Absorb water and minerals into plant roots by active transport

Where are stem cells found in adults?

Bone marrow

What are stem cells found in embryos called?

Embryonic stem cells

T or F: adult stem cells can differentiate into any types of cell.

F

How can stem cells be used to treat injury and disease?

They can replace faulty or damaged cells

Why are some people against embryonic stem cell research?

They think embryos shouldn't be used because each one is a potential human life

T or F: stem cell research is legal in the UK?

T

Where are stem cells found in plants?

Meristems

What can plant stem cells be used for?

To produce clones of plants quickly and cheaply

What can clones of plants be used for?

To grow more plants of rare species to prevent them from going extinct

What are chromosomes?

Coiled up lengths of DNA molecules

What does DNA stand for?

Deoxyribonucleic acid

What are genes?

Sections of DNA that code for the production of a specific protein

How many chromosomes does a normal human have?

46 (23 pairs)

What is the name of the series of stages where multicellular organisms produce new cells?

The cell cycle

What are the 2 stages of the cell cycle?

Interphase (growth)

Mitosis (division)

What happens during the first stage of the cell cycle?

The cell grows bigger and chromosomes and subcellular structures replicate

What are the 3 steps of mitosis?

The chromosomes line up in the middle of the cell and they are pulled apart

A membrane forms around both new sets of chromosomes to form two new nuclei

The cytoplasm and cell membrane divide

What is the term given to the cells produced by mitosis?

Daughter cells

T or F: daughter cells are genetically identical to the parent cell

T

What process do prokaryotic cells use to divide?

Binary fission

What are the 4 stages of binary fission?

Circular DNA and plasmids replicate

DNA moves to opposite ends of the cell

The cytoplasm divides and new cell walls form

2 new daughter cells are formed

How quickly can bacteria divide if given the right conditions?

As little as 20 minutes

Give 2 things that help maximise the rate of binary fission.

Warm temperature and lots of nutrients

What does a culture medium contain?

The carbohydrates, minerals, proteins and vitamins that bacteria being cultured need to grow

In what 2 forms can the culture medium be used in?

Nutrient broth solution or agar jelly

What is bacteria grown on?

Agar plates

What is the maximum temperature microorganisms are stored at in schools?

25 degrees celcius

How can equipment be sterilised before use?

Passing through a bunsen burner to kill any bacteria

Why are petri dishes stored upside down?

To prevent drops of condensation falling onto the agar surface

Define diffusion.

The net movement of particles from an area of high concentration to an area of lower concentration

How does a bigger concentration gradient affect the rate of diffusion?

It increases the diffusion rate

T or F: A higher temperature will give a slower diffusion rate.

F - a higher temperature will give a faster rate of diffusion

What word can describe membranes that only let certain substances through?

Partially permeable

Why does a larger surface area increase the rate of diffusion?

It allows more particles to pass through at the same time

Define osmosis.

The movement of water molecules from an area of high water concentration to an area of lower water concentration through a partially permeable membrane

How is osmosis different to diffusion?

DIffusion is the movement of particles, but osmosis is the movement of water only

Define active transport

The movement of substances from an area of low concentration to an area of higher concentration, requiring energy

Why do root hair cells have hairs that stick out into the soil?

To increase surface area

What is the role of a root hair cell?

Absorb nutrients and water from the soil into plants roots via active transport

Why can't root hair cells use diffusion to absorb minerals?

The concentration of minerals is usually higher in the cell than in the soil

Does active transport move along or against the concentration gradient?

Against

Why is active transport used in the small intestine?

To absorb nutrients into the bloodstream

What 3 things affect rate of diffusion?

DIffusion distance

Surface area

Blood supply (in animals

How does diffusion distance affect the rate of diffusion?

A shorter diffusion distance will increase the rate of diffusion as the particles have less distance to travel

How does surface area affect the rate of diffusion?

Larger surface area increases the rate of diffusion because it allows more particles to pass through at the same time

How does blood supply affect the rate of diffusion?

It allows substances to get in and out of the blood quickly

Where does gas exchange happen in the lungs?

Alveoli

Give 3 adaptations of alveoli that help them maximise diffusion.

Large surface area

Very thin cell wals

Good blood supply

Give 3 ways villi are adapted for gas exchange.

Large surface area

A single layered cells

Good blood supply

What are the names of the small holes that cover the underneath of the leaf?

Stomata

What 2 things diffuse out of the leaf through the stomata?

Oxygen and water vapour