biology paper 1

how are measles spread

Measles are spread through respiratory droplets when an infected person coughs or sneezes.

what are measles

viral infection that can cause blindness and brain damage

bacteria pathogens can cause harm to body by

producing harmful toxins

protease breaks proteins down

into amino acids

protease is found in

* small intestine
* stomach

amylase breaks down

starch into sugars

amylase is found in

small intestine and mouth

lipase is found in

* small intestine
* pancreas

lipases breaks down

lipids into glycerol and fatty acids

digestive enzymes

* lipase
* amylase
* protease

animal specialised cells

* muscle cells
* nerve cells
* sperm cells

sperm cells adaptations

* Sperm cells have a streamlined shape to aid in swimming
* They possess a flagellum for propulsion
* Sperm cells have a high concentration of mitochondria to provide energy for movement
* They have an acrosome, which contains enzymes to penetrate the egg's protective layer
* Sperm cells have a haploid nucleus, containing half the genetic material of a normal cell
* They are produced in the testes through the process of spermatogenesis
* Sperm cells are capable of fertilizing an egg to create a zygote
* They have a short lifespan, typically only surviving for a few days in the female reproductive tract.

differentiaion

process where cells change and become specialised

involves changing shape and structure

risks of using stem cells

* tumour development
* virus transmission

embryonic stem cells drawbacks

1. requires embryonic cells that have a limited supply
2. stem cells could be rejected by bodies immune system
3. ethical issues with using these stem cells

adult stem cells can divide by

mitosis

parts of plant cells that contain meristems are

1. tips of shoots
2. tips of roots

plant stem cells can consist for

plants entire lifetime

plant stem cells are found in …

meristems

adult stem cells can

* can only differentiate different types of blood cells
* divide by mitosis

where are adult stem cells found in

bone marrow

embryonic stem cells

cells that come from embryos and can differentiate into any kind of cell

stem cells

cells that can divide by mitosis to form new cells

before bacteria cells divide they have to

1. grow
2. replicate genetic material

how to work out the rate of reaction

1. total time / division time = division cycles
2. number of cells \* 2^ division cycles

binary fission step 5

cell splits in half and separates to form two identical bacteria cells

binary fission step 4

cell wall grows down the middle

binary fission step 3

genetic materials move to other sides of cell with plasmids that are distributed unequally

binary fission step 2

genetic materials replicates

binary fission step 1

bacteria cells grow

binary fission is a form of

form of asexual reproduction

bacteria grows in

* warm conditions
* plenty of nutrients conditions
* moist conditions

mitosis step 4

* cytokinesis - entire cells divide and form two identical daughter cells

mitosis step 3

* cell fibres pull the two arms of each chromosome to opposite sides of the cell

mitosis step 2

* chromosomes line up along the centre of the cell

mitosis step 1

* DNA condenses to form chromosomes

when cell is not divided DNA is …

Spread all over the cell

cytokinesis

division

new cells are used for

* growth
* development
* repair

electron microscope disadvantages

* hard to use - mainly used by scientists
* very expensive

electron microscope advantages

* uses electron instead of light
* resolution is 2000x better than light microscope
* can see sub cellular structures

light microscope disadvantages

* rely on light
* resolution is limited
* cannot see sub-cellular structures

light microscope advantages

* easy to use
* relatively cheap

why is magnesium needed for in plants

magnesium is needed for the production of chlorophyll

lack of of magnesium causes plant leaves to be yellow and chlorosis

why is nitrates needed in plants

needed for the production and synthesis of proteins

without proteins plants cannot grow so plants with nitrate deficiencies have a stunted growth

plants need many …

mineral ions for growth

they get these ions from the soil

plant diseases

rose black spot (fungal disease )

aphids (insects ) can feed on sap that stores sugars and divert these sugars away from plant

TMV (tobacco mosaic virus )

plant defences

mechanical defences

physical defences

chemical defences

chemical defences

antibacterial chemicals are produced by some plants example of these are witch hazel , mint and garlic )

some plants produce poisons to deter herbivories

mechanical defences

thorns and spikes to put off any predators

some plants use mimicry to trick animals

leaves close up decrease the surface area available to herbivories

physical defences

bark is used as a physical barrier against insects

waxy cuticle outside leaves create a barrier that stop pathogens from invading the plant

cell walls are made of cellulose which is also a physical barrier that stops pathogens from entering

where is sap found in the plant

phloem

what are monoclonal antibodies produced from

clones of cells

lymphocytes

white blood cells

myeloma cells

tumour cells

producing monoclonal antibodies

1. a mouse is injected with a chosen antigen obtained from a pathogen


2. the mousses immune system responds by producing lymphocytes (white blood cells )
3. lymphocytes are extracted from my myeloma cells (tumour cell)
4. the tumour cells grow rapidly and produce lots of identical cells
5. all the hybridoma cells produce the same antibody
6. these monoclonal antibodies can be collected and purified and can be used to target specific cells

pregnancy tests

monoclonal antibodies bind to the HCG hormones antigens produced by pregnant woman

identifying chemicals

monoclonal antibodies can identify the levels or hormones

in the blood to find the presence of pathogens like HIV

phagocytosis

when a white blood cell finds a pathogen and engulfs it , this destroys the pathogen

function of white blood cell

produce antitoxins

produce antibodies

phagocytosis

virus

tiny non-living organisms that can reproduce in the body

antitoxins

neutralise the toxins released by bacteria so they don’t cause any harm

fungi

Fungi are unicellular or multicellular organisms that each have bodies made up of hyphae.

hyphae

are able to grow and penetrate tissues and ten the hyphae produce spores

vectors for malaria

female anopheles mosquito

bacteria reproduce in

moist and warm condition with a good supply of oxygen

parasites

living inside or on other organisms

plant organs

roots

stems

reproductive structure

leaves

spongy mesophyll

helps with gas exchange

stomata

makes diffusion easier in and out of the leaf

epidermal tissue

covers the outer surface of leaves

palisade mesophyll

located upper epidermis

have lots of chloroplasts

root hair cells absorb water via

osmosis

mineral ions get taken up through

active transport

transpiration

xylem

water only moves in one direction

rate of transpiration can be increased by ..

temperature

humidity

light intensity

airflow

translocation

phloem tubes

bidirectional

allows sap to pass through cells both ways

translocation process

Translocation is the process by which food produced in photosynthesis is transported from the leaves to the growing regions of plants and storage organs.

magnification

how many times larger an image is seen through a microscope compared to a real object

resolution

the ability to distinguish between two or more objects that are really close

magnification equation

image size/ actual size

eukaryotic cells

* plant
* animal

prokaryotic cells

bacteria cells

unicellular

1 cell organism

cells

smallest unit of like that can replicate independently

cell membrane

control substances that pass in and out of the cell

nucleus

contains genetic material / DNA

cytoplasm

where chemical reactions take place

mitochondria

provides cells with energy needed to function for aerobic respiration

ribosomes

site of protein synthesis so where proteins are made

cell wall

support and structure

permanent vacuole

contains cell sap

chloroplasts

photosynthesis

animal cell contains

* cell membrane
* nucleus
* cytoplasm
* mitochondria
* ribosomes

plant cells contain

* cell membrane
* nucleus
* cytoplasm
* mitochondria
* ribosomes
* cell wall
* permanent vacuole
* chloroplasts

bacteria cells have

* cytoplasm
* cell wall
* cell membrane
* ribosomes
* plasmids
* flagella
* circular strands of DNA

bacteria cells don’t have

* nucleus
* ribosomes
* chlorophasts

plasmids

extra genes (antibiotic resistance )

flagella

help move / propel bacteria

parts of microscope

* base
* arm
* light source (lamp / mirror)
* stage
* microscope slide
* objective lenses (different magnification )
* eyepiece lenses (fixed magnification)
* body tube
* coarse focusing knob