Biology ✿ cells (FULL TOPIC)

eukaryotic cells (animal and plant cell)

cells which store DNA in a nucleus

prokaryotic cells (bacteria cell)

cells which store DNA as plasmids

state 2 differences between prokaryotic and eukaryotic cells

• prokaryotic cells are smaller

• prokaryotic cells store genetic material in a plasmid

what 2 cell structures are only found in the plant cell?

• chloroplasts

• permanent vacuole

state the function of a nucleus

to control the cell and store genetic material

state the function of a ribosome

to synthesis protein

state the function of cytoplasm

the site where chemical reactions take place

state the function of a cell membrane

controls what subtances enters and leaves the cell by diffusion

state the function of mitochondria

site where aerobic respiration takes place and release energy

state the function of a cell wall

strengthens and supports the cell

state the function of chloroplasts

site where photosynthesis happens

state the function of a permanent vacoule

keeps cell rigid to support the plant

what is a cell wall made up of?

cellulose

specialised cell

a cell that has specific functions and structures so it can carry out a particular job

state 2 adaptations and their functions of a root hair cell

• thin walls → to allow more water to be absorbed easily by osmosis

• long and thin → increases surface area for more mineral uptake

state 3 adaptations and a function of a xylem cell

transports water and minerals from roots to the plant

• no end walls between cells to allow water to pass through easily

• thick walls lined with lignin to support the plant

• cells are dead and hollow allows water to pass through easily

transpiration

The evaporation of water from leaves

state 2 adaptations and their functions of a phloem cell

• sieve tubes between cells → allow dissolved sugars to move through phloem

• companion cells → provides energy for active transport of sugars out of phloem

state 2 adaptations and their functions of a sperm cell

• long tail → allows sperm to swim to egg

• enzymes in the head → allows sperm to fertilise the egg

state 2 adaptations and their functions of a nerve cell

• long axon → to carry electric impulses over long distances quickly

• myelin sheath around axon → insulates axon to speed up transmitting of electric impulses

state 2 adaptations and their functions of a muscle cell

• a lot of mitochondria → to provide energy for muscle movement

• long and can contract → allows muscle to move

differentiation

the process of unspecialised cells forming different types of specialised cells to carry out specific jobs

when does differentiation happen in an animal?

early stage of development

when does differentiation happen in a plant?

throughout life

resolution

the ability to distinguish between 2 objects (the smallest measurment)

magnification

how much bigger the image is than the actual object

why are electron microscopes better than light microscopes?

they have a greater magnification and resolution which allow more subcellular structures to be seen

equation for magnification

size of image / size of real object

nucleus

contains chromosomes made of DNA molecules

chromosomes are found __ ____

in pairs

why is mitosis important?

helps with growth, repair and asexual reproduction

what are the 3 stages of the cell cycle

1. DNA replicates and forms 2 copies of each chromosome and it’s subcellular structures

2. mitosis; each set of chromosomes are pulled to each end of cell and nucleus divides to form two new nuclei

3. cytoplasm and cell membrane splits, 2 genetically identical daughter cells are formed

what happens during mitosis?

• chromosomes are duplicated and are pulled apart

• nucleus divides and forms 2 new nuclei

• forming 2 genetically identical daughter cells

where does mitosis occur?

everywhere in the body except in the gametes

stem cell

undifferentiated cells that can form specialised cells

where are stem cells found in a human and in a plant?

human

• embryos

• bone marrow

plants

• meristem tissue

what are stem cells from adult bone marrow only used for

blood cells

what are stem cells from embryos used for?

to treat diabetes and paralysis

what are stem cells from plants/ meristems used for?

to preserve rare species and to produce more disease resistant crops

state 1 advantage and 2 disadvantages of embryonic stem cells

advantage

• not rejected by body

disadvantage

• risk of viral transmission

• ethical/ religious objections

diffusion

the movement of gas particles down a concentration gradient

give 3 factors which affect the rate of diffusion

• difference in concentrations

• temperature

• surface area of membrane

how can you give an object a larger surface area to volume ratio?

cut it up in smaller pieces

state 4 ways the small intestines are adapted for absorption (exchanging materials)

• villi provide a larger surface area

• villi are one cell thick to allow faster diffusion

• good blood supply maintains concentration gradient

• long for more absorption time

state 4 ways the lungs are adapted for exchange of oxygen and carbon dioxide with the blood

• alveoli are one cell thick allow faster diffusion

• alveoli provides large surface area

• moist surface allows gases to diffuse

• continually ventilated to bring in more oxygen and maintains concentration gradient

state 3 ways fish gills are adapted for uptake of oxygen from the water

• thin layer allows faster diffusion

• good blood supply maintains concentration gradient

• well ventilated to bring in more oxygen and maintains concentration gradient

state 3 ways plant roots are adapted for uptake of water from the soil

• root hair cells increase surface area

• hairs are one cell thick for quick diffusion

• a lot of mitochondria to transfer energy for active transport

state 3 ways plant leaves are adapted for gas exchange

• flat and thin for quick diffusion

• air spaces in spongey mesophyll allow gases to move easily

• stomata allow gases in and out leaf

osmosis

the movement of water from a dilute to concentrated solution through a partially permeable membrane

active transport

movement of substances across a cell membrane against the concentration gradient

why is active transport necessary in plants?

• allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil

• this allows plant to grow healthy

why is active transport necessary in the gut?

• allows sugar molecules to be absorbed from lower concentrations in the gut into the blood

• sugar molecules are used for cell respiration

which transport process require energy?

active transport

which transport processes dont require energy?

diffusion and osmosis

Transpiration stream

The continuous flow of water from the roots to the leaves through the xylem

What process occurs in the xylem?

Translocation

What process occurs in the phloem?

Transpiration