Biology Stuff I need to know

Phosphate ions in plants

contains phosphorus for making DNA and cell membranes → needed for respiration and growth and without it there is poor root growth and purple leaves

Potassium ions in plants

To help enzymes and needed for photosynthesis and respiration. Without it there is poor flower and root growth and discoloured leaves

energy released from food (J)

mass of water x temp rise x 4.2/ mass of food sample

function of the nucleus

Controls what substances are made by the cell and controls cell activities

Ribosomes

Where proteins are synthesized

Cell wall

Provides strength and protection and made of cellulose

importance of cell differentiation in the development of specialised cells

allows organisms to form tissues and organs

cell differentiation

the process by which stem cells can be specialised into different types of cells

stem cells are

undifferentiated, can divide via mitosis, able to self-renew

Embryonic stem cells

• can be extracted from embryos up to 5 days

• can self-renew

• totipotent so can differentiate into any cell

Adult stem cells

• found in developed humans

• can self renew

• used for growth and repair by the organism

Meristem cells

• found in plants tissues ( shoots and roots)

• self renew

• totipotent

pros of using stem cells

• repair and replace damaged tissue

• bone marrow transplants for blood immune disorders

• embryonic stem cells more useful

• can be used to develop organs instead of waiting on a transplant

cons of using stem cells

• ethics of the embryo

• less number of stem cell donors

• risk of disease: can become infected in a lab

• High cost of availability and storage ( umbilical chord blood)

starch and glycogen are polymers of

carbohydrates ( simple sugars)

enzyme pH practical

use a buffer solution with a different pH level

high surface area to volume ratio =

a higher rate of diffusion

Adaptations of a leaf

Green: has chlorophyll for photosynthesis

Thin: shorter diffusion distance for gases from bottom

Wide: the high area for sunlight to land on, so high surface area for gases

Moisture in air spaces: allows gases to dissolve which increases diffusion rate

Transpiration

The evaporation of water from the surface of a plant

transpiration stream

1. water enters root hair cells by osmosis

2. Water moves through the root cortex by osmosis

3. Water moves into the xylem

4. Water is drawn up the xylem

5. Water enters the mesophyll cells

6. Water evaporates and leaves through the stomata

potometer experiment

• cut diagonally and underwater to prevent air bubbles forming

• dry leaves of the shoot as wet leaves affect transpiration and put petroleum jelly to seal any gaps

• remove the capillary and allow a single air bubble and place the tube back into water

• record the distance the bubble moves

potometer oil is for

stopping water from evaporating out of flask

stomata that are flaccid are

closed

stomata that are turgid are

open

why is the potometer experiments only an estimation

because of photosynthesis and also respiration

phagocytes

ENGULF- they detect foreign bodies then engulf them and digest them because they contain digestive enzymes. they are non specifc

Lymphocytes

• every pathogen has antigens on its surface and when lymphocytes detect the foreign antigen they produce antibodies which mark them for phagocytes to engulf

• antibodies are specific so won’t bind to others

• memory cells are also produced in response to a foreign antigen and remains in the blood stream

a bruise

a trapped pool of blood

blood clotting

1. blood vessel becomes damaged by force or by cuts

2. when exposed to collagen, platelets become activated and they become sticky and spiky

3. they stick to the open site

4. the activated platelets release clotting factors

5. clotting factors start a chain reaction that changes fibrinogen (a soluble protein in the blood) into fibrin

6. Fibrin forms a mesh across the wound

7. RBC get trapped in the fibrin mesh

8. The RBC, platelets and fibrin dries out and forms a scab

auxin is

broken down by light and inhibits growth in the roots and promotes growth in the shoots

auxin in the roots

darker side grows slower and the root grows downwards

auxin in the shoots

leads to asymmetrical growth as darker side grows faster

synaptic transmission

1. electrical impulse arrives at first neuron

2. vesicles containing neurotransmitters attach to the neuron membrane

3. the vesicles release the neurotransmitters into the synaptic cleft

4. the neurotransmitters bind to the receptors on the membrane of the 2nd neuron

5. this triggers a new electrical impulse

the CNS consists of

brain and spinal chord

reflex arc

1. the stimulus is detected by the receptor cells

2. a sensory neuron sends electrical impulses to the spinal chord

3. an electrical signal is passed to a relay neuron in the SC

4. a relay neuron synapses with a motor neuron

5. a motor neuron carries an impulse to a muscle or gland ( the effector)

what is a reflex

a rapid, automatic (involuntary) response to a stimulus

insulin

lowers blood glucose levels

glucagon

raises blood glucose levels

thyroxine

regulates metabolism and growth

Menstrual cycle

FSH, Oestrogen, LH, Progesterone

FSH

• causes the follicle to develop an egg

• stimulates oestrogen

Oestrogen

• Builds up uterus lining

• triggers LH and inhibits FSH

LH

• Triggers ovulation

• Stimulates progesterone

• Inhibits oestrogen

genome

the entire DNA of an organism

gene

a section of DNA that codes for a specific protein

DNA structure

2 strands coiled to form a double helix

RNA structure

Single stranded and contains uracil instead of thymine

alleles

alternative forms of a gene

Transcription on PS

1. DNA strands are separated by RNA polymerase in the nucleus and breaks the hydrogen bonds

2. DNA polymerase then binds mRNA nucleotides to their complementary base pair

3. A mRNA molecule is formed

Translation in PS

1. mRNA binds to the ribosome

2. Each tRNA binds to its anticodon which brings together a specific sequence of amino acids

3. The amino acids bind together to form a protein

codominace meaning

both alleles within a genotype are expressed

most phenotypic features are a result of

polygenic inheritance rather than single genes

dominant

will always be expressed

recessive

only expressed in a homozygous form

mitosis

1. chromosomes duplicate

2. chromosomes condense

3. the sister chromatids line up at the equator

4. they split apart and are pulled either side of the nucleus by spindle fibres

5. 2 new nuclei form

meosis

divides twice

purpose of meiosis

the production of gametes

facts about meosis

• 2 divisions

• 4 genetically different cells

• forms 4 gametes

facts about mitosis

• 1 division

• 2 genetically identical clones

• somatic (body) cells

• diploid

purpose of mitosis

• growth and repair of tissues

• asexual reproduction for unicellular organisms

mutations are

rare, random changes in genetic material that can be inherited

ecosystem

all the organisms living in a particular area and all the abiotic conditions

habitat

the place where an organism lives

population

all the organisms of 1 specie in a particular habitat

community

all the populations of different species in a particular habitat

quadrat formula

total area/ area of 1 quadrat X average individuals per quadrat

triple quadrat what’s it for

the distribution of how an abiotic factor changes

cons of quadrats

can lead to overestimation as you count every single one

pyramid of numbers

does not always have to be a pyramid

order or trophic levels

1st: Producers

2nd: Primary

3rd: Secondary

4th: Tertiary

only 10% transferred up the food chain becuase

excretion, respiration, movement, not all of animal is eaten

effects of deforestation

leaching: soil minerals are not taken up by trees and are instead washed away by rain into nearby bodies of water

soil erosion: not held together by tree roots and organic matter

Water cycle disturbance: the removal of trees reduces photosynthesis so less carbon dioxide removed from atmosphere and stored in plant tissues

calcium ions needed for in plants

cell walls and membranes. without it, it has deformed new leaves and stunted growth

glasshouses are for

protecting plants from the outside environment

polythene tunnels are for

protecting against wind but cannot control O2 and CO2 and it portable

irrigation system in glasshouses and polythene tunnels

provides fertilisers and water

pros of pesticide

• immediate

• kills entire population

• easily accessible

cons of pesticide

• may develop resistance

• bioaccumulation

• may kill beneficial organisms

pros of biological control

• natural

• no resistance

• long lasting

• targets specific species

• only applied once

cons:

• can eat useful organisms

• takes longer to be effective

• might not adapt

recombinant

DNA that has been genetically altered

transgenic

the transfer of genetic material from one species to a different species

Yoghurt

Lactobacillus converts lactose into lactic acid

Yeast in bread

produces enzymes which break down starch in flour and it respires anaerobically producing Co2 and its trapped in small air pockets which causes the dough to rise

Fish farming is for

A source of protein for humans to eat