N5 BIO multicellular organisms

chromosome complement

number of chromosomes a cell contains

reasons for cell division

* reproduce (unicellular)
* growth and repair (multicellular)

diploid

cell with a double set of chromosomes

unicellular

organism composed of one cell

mulitcellular

organism composed of multiple cells

its important the chromosome compliment in daughter cells is maintained so that…

no information is lost and the cell can carry out the same functions as the parent cell

mitosis stage 1 & 2

1. each __chromosome doubles__ to form 2 identical __chromatids__
2. __chromosomes__ shorten & coil up. __Nuclear membrane__ starts to disappear

mitosis stage 3 & 4

3. __chromatids__ line up at the __equator__ and __spindle fibres__ attach to the __centromeres__
4. spindle fibres __pull apart__ pair of identical chromatids to __opposite poles of the cell__

mitosis stage 5 & 6

5. __new nuclear membranes form__, cytoplasm divides
6. 2 daughter cells are formed, the __daughter cells are identical to each other and the parent cell__

embryonic stem cells

* found in very early embryos
* have ability to develop into any type of cell the body requires
* can develop into complete organs

tissue/adult stem cells

* only regenerate cells associated with the tissues in which they are found

stem cells

* unspecialised cells found in animals
* can divide to produce more stem cells

specialised cell

cell that has become differentiated to perform a specific function e.g. nerve cell, red blood cell, sperm cell

therapeutic application of stem cells

* bone marrow transplant
* skin grafts
* repairing heart muscle
* cornea repair

organise cell types

cells → tissue → organs → systems

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e.g.

muscle cells → muscle tissue → heart → circulation system

main parts of CNS

* brain
* spinal cord

CNS is connected to the rest of the body by…

neurons (nerves)

brain

cerebrum

controls conscious thoughts, memory and personality

cerebellum

controls muscle coordination and balance

medulla

controls breathing and heart rate

CNS system

stimulus→ receptor→ sensory neuron→ inter neuron(in CNS)→ motor neuron→ effector→ response

reflex arc

* rapid reflex actions provides protection against possible harmful stimuli

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* e.g. swallowing-(stimuli=touch/pressure)-(effect=muscle contract)-(protective role=prevent choking)

synapse

* the space where two neurons meet

hormones

chemical messengers produced by endocrine glands

factors that increase risk of diabetes

* overweight
* age
* genetics (type 1)

type 1 diabetes

* early, rapid onset
* no insulin produced
* requires injections

type 2 diabetes

* overweight, elderly
* resistance to insulin
* healthy, balanced lifestyles

pancreas detects increase in blood sugar…

insulin released → insulin converts glucose into glycogen to remove glucose from blood → normal blood sugar level

pancreas detects decrease in blood sugar…

glucagon release increased → glucagon broken down into glucose → normal blood sugar level

H__i__ → __i__nsulin

(high blood sugar)

glucose is gone → glucagon

(low blood sugar)

diploid cells

each cell contains two matching sets of chromosomes

haploid cells

each cell contains one set of chromosomes

fertilisation

the nucleus of the male gamete: sperm (haploid) fuses with the nucleus of the female gamete: egg (haploid) to form a zygote (diploid)

plant

plant male gamete

pollen produced in the anther

plant female gamete

ovule produced in the ovary

animal male gamete

sperm produced in the testis

animal female gamete

egg cell produced in the ovary

male

female

fertilisation in animals occurs inside…

the female in the oviduct

continuous variation

the inherited characteristic shows a range of values between a minimum to a maximum (cannot be put in distinct groups e.g. height)

discrete variation

the characteristic cannot be measured so forms distinct groups with no continuation of the characteristic in between e.g. eye colour

polygenic inheritance

* most phenotypes show continuous variation
* type of inheritance involving several genes acting together

gene

section of DNA strand that codes for a protein that gives the organism its characteristics

allele

different forms of a gene

phenotype

description if the appearance of the organism

genotype

the genes that an organism possesses, giving rise to the phenotype

homozygous

organism that has a genotype with 2 identical alleles either dominant or recessive

heterozygous

organism that has a genotype with 2 different alleles, one dominant and a hidden recessive allele

the reason why actual results differ is…

because fertilisation is a random process. Introducing the element of chance

upper epidermis function

thin outer layer - has no chloroplasts so allows light to pass through to mesophyll cells

palisade mesophyll function

* main site of photosynthesis
* cells contain many chloroplasts
* cells arranged to allow maximum absorption of light energy

spongy mesophyll function

cells are loosely packed with moist air spaces between them to allow gases to diffuse quickly into the cells

vein

contains xylem and phloem vesseles

lower epidermis

lower layer of cells containing many pores called stomata (singular, stoma)

stoma

allows water vapour to leave and is site of gas exchange

guard cells

* cells that surround the stomata & control the opening and closing of the stomata
* stomata allow entry and exit of excess water vapour and oxygen

use of transport systems in plants

* allow water and minerals to travel to leaf cells
* allow sugar to move around

water & soil minerals are absorbed through…

root hair cells by osmosis and transported up the plant to the leaves in xylem

xylem vessels

* dead hollow tubes
* water and minerals move in upward direction
* supports the plant due to lignin

xylem is supported by…to…

* lignin
* to withstand changes in pressure as water moves up the plant

transpiration

loss of water by the evaporation from the leaves of a plant

why do root hairs have a large surface area?

to increase absorption of water

factors affecting rate of transpiration

* change in temperature
* change in wind speed
* change in humidity
* surface area

transport of sugar

* transported in phloem tissue
* phloem tissue is alive
* sugars move up and down
* phloem is made up of: sieve tubes, companion cells

potometer

measure rate of transpiration/rate of water uptake

red blood cell

* carries oxygen around the body
* biconcave
* contain haemoglobin
* don’t have a nucleus

white blood cell

protects body from infection

plasma

liquid component of blood in which cells and other materials are carried

blood transports

* oxygen
* carbon dioxide
* glucose

RBC equation

haemoglobin + oxygen (lungs)

white blood cells destroy

pathogens

pathogens

* bacteria
* fungi
* virus

main types of white blood cell

1. phagocytes
2. lymphocytes

phagocytes

destroy pathogens through a process called phagocytosis

lymphocytes

* produce antibodies which destroy pathogens
* each antibody is specific to a particular pathogen

phagocytosis

1. phagocyte moves towards pathogen
2. phagocyte engulfs pathogen
3. pathogen destroyed by enzymes in phagocyte

left ventricle has a thicker muscle than right ventricle bc…

right ventricle only pumps blood a short distance to the lungs but the left ventricle pumps blood a greater distance to all other body parts

valves are found…

between the atria and ventricles and between the ventricle and the arteries leaving the heart

function of valve

prevent backflow of blood

artery

* function: carries blood away from the heart at high pressure
* structure: thick muscular walls to withstand pressure & narrow central cavity

vein

* function: carries blood towards the heart at low pressure
* structure: contain valves to prevent backflow of blood, wide central cavity & thick muscular wall (but not as thick as artery)

capillaries

* smallest blood vessel
* found in dense networks close to body cells
* where exchange of materials between blood and body cells take place

capillary features

* very thin walls- fast exchange of gases and nutrients
* found in dense networks- rich blood supply so more exchange of materials
* large surface area- maximum exchange of materials

coronary arteries

blood supply to the heart muscle

blood flow through the heart, lungs & body (deoxygenated blood)

vena cava → right atrium → right ventricle → pulmonary artery → lungs

blood flow through the heart, lungs & body (oxygenated blood)

lungs → pulmonary vein → left atrium → left ventricle → aorta → body cells + tissue-(also deoxygenated)

aorta

carries blood away from the heart

atria

Upper chambers of the heart that pass blood to the lower ventricles

pulmonary artery

Artery that carries deoxygenated blood from the heart to the lungs

pulmonary vein

Vein that carries oxygenated blood from the lungs to the heart

vena cava

Blood vessels that carry deoxygenated blood to the heart from the body

ventricles

Lower chambers of the heart that receive blood from the upper atria

materials required to be absorbed into cells

* oxygen for respiration
* nutrients

waste material that needs to be removed from cells

carbon dioxide

where do materials travel around the body

bloodstream

features of surfaces that carry out absorption exchange

* large surface area
* thin walls
* rich blood supply

lungs

* gas exchange organs
* have a large number of alveoli