N5 BIO multicellular organisms

number of chromosomes a cell contains

• reproduce (unicellular)

• growth and repair (multicellular)

cell with a double set of chromosomes

organism composed of one cell

organism composed of multiple cells

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

1. each chromosome doubles to form 2 identical chromatids

2. chromosomes shorten & coil up. Nuclear membrane starts to disappear

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

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

• found in very early embryos

• have ability to develop into any type of cell the body requires

• can develop into complete organs

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

• unspecialised cells found in animals

• can divide to produce more stem cells

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

• bone marrow transplant

• skin grafts

• repairing heart muscle

• cornea repair

cells → tissue → organs → systems

e.g.

muscle cells → muscle tissue → heart → circulation system

• brain

• spinal cord

neurons (nerves)

controls conscious thoughts, memory and personality

controls muscle coordination and balance

controls breathing and heart rate

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

• rapid reflex actions provides protection against possible harmful stimuli

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

• the space where two neurons meet

chemical messengers produced by endocrine glands

• overweight

• age

• genetics (type 1)

• early, rapid onset

• no insulin produced

• requires injections

• overweight, elderly

• resistance to insulin

• healthy, balanced lifestyles

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

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

glucose is gone → glucagon

(low blood sugar)

each cell contains two matching sets of chromosomes

each cell contains one set of chromosomes

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

pollen produced in the anther

ovule produced in the ovary

sperm produced in the testis

egg cell produced in the ovary

the female in the oviduct

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

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

• most phenotypes show continuous variation

• type of inheritance involving several genes acting together

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

different forms of a gene

description if the appearance of the organism

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

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

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

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

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

• main site of photosynthesis

• cells contain many chloroplasts

• cells arranged to allow maximum absorption of light energy

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

contains xylem and phloem vesseles

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

allows water vapour to leave and is site of gas exchange

• cells that surround the stomata & control the opening and closing of the stomata

• stomata allow entry and exit of excess water vapour and oxygen

• allow water and minerals to travel to leaf cells

• allow sugar to move around

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

• dead hollow tubes

• water and minerals move in upward direction

• supports the plant due to lignin

• lignin

• to withstand changes in pressure as water moves up the plant

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

to increase absorption of water

• change in temperature

• change in wind speed

• change in humidity

• surface area

• transported in phloem tissue

• phloem tissue is alive

• sugars move up and down

• phloem is made up of: sieve tubes, companion cells

measure rate of transpiration/rate of water uptake

• carries oxygen around the body

• biconcave

• contain haemoglobin

• don’t have a nucleus

protects body from infection

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

• oxygen

• carbon dioxide

• glucose

pathogens

• bacteria

• fungi

• virus

1. phagocytes

2. lymphocytes

destroy pathogens through a process called phagocytosis

• produce antibodies which destroy pathogens

• each antibody is specific to a particular pathogen

1. phagocyte moves towards pathogen

2. phagocyte engulfs pathogen

3. pathogen destroyed by enzymes in phagocyte

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

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

prevent backflow of blood

• function: carries blood away from the heart at high pressure

• structure: thick muscular walls to withstand pressure & narrow central cavity

• 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)

• smallest blood vessel

• found in dense networks close to body cells

• where exchange of materials between blood and body cells take place

• 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

blood supply to the heart muscle

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

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

carries blood away from the heart

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

Artery that carries deoxygenated blood from the heart to the lungs

Vein that carries oxygenated blood from the lungs to the heart

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

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

• oxygen for respiration

• nutrients

carbon dioxide

bloodstream

• large surface area

• thin walls

• rich blood supply

• gas exchange organs

• have a large number of alveoli