B1 - Cells

missed topics June 22 mean division time sugar solutions in plants fish gills

Cell

smallest unit of life

Eukaryotic cells

more complex cells, part of multicellular organisms

Prokaryotic cells

simpler cells, bacterial cell

Prokaryote

a unicellular organism

Eukaryote

an organism made from eukaryotic cells

What are the 2 types of eukaryotic cells?

animal and plant

Nucleus

controls the cell and contains genetic material

Cytoplasm

substance in which most chemical reactions happen

Cell membrane

controls substances that enter and exit the cell

Mitochondria

where aerobic respiration takes place

Ribosomes

site of protein synthesis

Cell wall

supports and protects cell, made of cellulose

Vacuole

contains cell sap

Chloroplasts

site of photosynthesis, contains chlorophyll

Which feature do plant cells have that animal cells don't?

cell wall, chloroplasts, vacuole

What are the 2 types of microscope?

light and electron

What is the formula for magnification?

magnification \= image size / actual size

1mm \= ?μ ?

1000

Specialised cells

Cells that are adapted to carry out a specific function

Differentiation

process of a cell becoming specialised

What a sperm cells specialised for?

reproduction

What are the adaptions of a sperm cell?

streamlined, tail, lots of mitochondria, enzymes

Why does sperm have a streamlined shape and tail?

to help it swim

Why does sperm have lots of mitochondria?

to have lots of energy to reach egg

Why does sperm have enzymes in its head?

to break enamel of egg

What is a nerve signal specialised for?

rapid signalling

What is the adaption of a nerve cell?

long

Why are nerve cells long?

to carry electrical signals all around the body

What is the adaption of a muscle cell?

lots of mitochondria

Why does a muscle cell have lots of mitochondria?

to have enough energy to contract quickly

What is a root hair cell specialised for?

Absorbing water and minerals

What is the adaptation of a root hair cell?

large surface area

Why does a root hair cell have a large surface area?

to absorb large amounts of water and minerals

Mitosis

the process of eukaryotic cell division when the cells divide

What processes must happen before mitosis?

increase number of subcellular structure, duplicate DNA

Binary fission

the process of prokaryotic cell division

What are good conditions for bacteria reproduction?

warm, lots of nutrients

Culture medium

a nutrient solution or agar jelly in/on which bacteria in cultured

How are agar plates made?

agar jelly poured into Petri dish, microorganisms added to the plate, bacteria multiplies

How are microorganisms added to the plate?

innoculating loop or pipette and spreader

In school what is the max temp. agar plates are kept at?

25°C

Why are agar plates not kept above 25°C?

In case harmful pathogens are produced

How can the effect of antibiotics on bacterial growth be investigated?

soaking paper discs in antibiotics, adding to an agar plate, left for 48hrs, measure diameter of inhibition zone

How can the conditions be regulated?

aseptic method

stem cells

undifferentiated cells

What are the 2 types of stem cell?

adult, embryonic

embryonic stem cell

stem cells able to differentiate into any type of cell

adult stem cell

stem cells able to differentiate into 1 type of cell

Give 3 examples of where adult stem cells are found?

bone marrow, brain, hair

What do adult stem cells in the bone marrow make?

blood cells

Therapeutic cloning

producing embryonic cells with the same genetic information as the patient

Pros of therapeutic cloning

replace faulty cells, body will not reject transplanted cells

Cons of therapeutic cloning

risk of contamination, ethics

Where are stem cells found in plants?

meristems

How can plant stem cells be used in agriculture?

develop drought, flood, disease resistant crops

Diffusion

movement of particles from a higher to a lower concentration

concentration gradient (diffusion)

different between concentrations

osmosis

diffusion of water

active transport

absorption of a substance against the concentration gradient (low

Where do plants get energy for active transport from?

respiration

Where do humans get energy for active transport from?

glucose from gut or kidneys

How is active transport used in digestion?

transport glucose from small intestine to bloodstream

Why is a large surface to volume ratio important?

to absorb or exchange the most substance

exchange surface

surface where substances are exchanged

How are alveoli adapted for gas exchange?

large surface area, blood supply, thin walls, moist lining

Why do alveoli have a moist surface?

to help dissolve gases to exchange them quicker

How is the small intestine adapted for diffusion and active transport?

villi, single cell walls, capillaries

How is a leaf adapted for gas exchange?

flattened shape, stomata, guard cells, air space

Why do leaves' flattened shape help gas exchange?

large surface area

How do guard cells help gas exchange?

control stomata

Why do stomata help gas exchange?

to close when to much water vapour is lost

How does air space in leaves help gas exchange?

more space for gases to enter leaf

Where is a leaf's exchange surface?

lower epidermis

What is the exchange surface on a fish?

gills

How do gills work?

water enters through the mouth and out the gills, oxygen diffuses into gills and carbon dioxide out

What makes gills good at exchanging substances?

gill filaments covered in lamellae - large surface area

lots of capillaries - good blood supply

thin surface area - easy diffusion

blood and water flow in opposite directions - high concentration gradient

turgor pressure

pressure created by vacuole against cell wall