Biology Paper 1 Topic 2 - Scaling Up

What is diffusion?

the net movement of particles from an area of high concentration to an area of low concentration

What is active transport?

molecules move against the concentration gradient from an area of low concentration to an area of high concentration, which requires energy

What is osmosis?

the net movement of water from a high water potential to a low water potential through a partially permeable membrane

What moves into and out of cells by diffusion?

in: oxygen and glucose, out : carbon dioxide

what is glucose moved from?

the intestine into the blood stream by active transport

does a dilute solution/concentrated solution have a high or low water potential?

dilute - high water potential, concentrated - low water potential

What is mitosis?

The division of cells to produce new cells

Why are new cells needed?

to replace those that die or are damaged

Stages of mitosis

1. parent cell contains chromosomes, 2. chromosomes are copied, 3. chromatids pull apart, 4. two new cells are created, each identical to parent

how does mitosis allow organisms to reproduce?

asexually

what is cell differentiation?

when one cell changes into another type of cell

What is cell differentiation like in animals?

it happens at an early stage of development, and occurs to create specialised cells. In mature animal cells, it is mostly restricted to replacement and repair

what are some examples of specialised cells?

root hair cells, ovum, xylem, sperm cell and nerve cells

what are stem cells?

undifferentiated cells that can differentiate to form specialised cells, such as muscle cells or nerve cells

where can human stem cells come form?

human embryos, in umbilical cord blood from new born babies or from adult bone marrow

can embryonic stem cells differentiate into any type of cell?

yes

what can adult stem cells differentiate into?

only into the cells of the type of tissue from which they came

where are plant stem cells found?

meristematic tissue, which is usually in the tips of shoots and roots

what can stem cells be used for?

testing new drugs

what do stem cells have the potential to provide?

replacement cells, and tissues to treat Parkinson's disease, burns, heart disease and arthritis.

ethical issues surrounding the use of stem cells

is destroying embryos taking a life? is it right to dispose of human embryos? who decided which people should benefit from such a treatment?

what do exchange surfaces allow?

efficient transport of materials across them by mechanisms such as diffusion and active transport

what does the cell membrane provide in unicellular organisms?

an efficient exchange surface

what do multicellular organisms have?

a smaller surface area to volume ratio, and developed specialised exchange surfaces

what substances need to be exchanged and transported?

oxygen and carbon dioxide, dissolved food molecules such as glucose and minerals, urea and water

what should an efficient exchange system have?

a large surface area to volume ratio, membranes that are very thin so diffusion distance is short, a good supply of transport medium

what are the two loops in the human circulatory system?

one from the heart to the lungs, one from the heart to the body

what type of circulatory system do humans have?

a double circulatory system

an advantage of a double circulatory system

it can achieve a higher blood pressure and a greater flow of blood and oxygen to tissues

what are substances transported by the circulatory system?

oxygen, carbon dioxide, dissolved food molecules, hormones, antibodies, urea and other waste products

what do the left and right side of the circulatory system carry?

right - deoxygenated blood, left - oxygenated blood

what does the vena cava do?

carries deoxygenated blood back to the heart

what does the pulmonary artery do?

carries deoxygenated blood from the heart to the lungs

what does the pulmonary vein do?

carries oxygenated blood from the lungs to the heart

what is the aorta?

the main artery that leaves the heart and supplies oxygenated blood to the body

what does blood containing high levels of co2 do?

it returns to the heart

what does blood containing high levels of oxygen do?

it flows to the cells in the body

what happens in the lungs?

oxygen and glucose are supplied the cells and carbon dioxide and waste are removed from the cells

what does the heart do and what is it mostly made of?

it pumps blood to the lungs and around the body

made of mostly muscle

what does the left ventricle need to do?

pump blood around the whole body so it has thicker, more muscular walls

why are there valves between atria and ventricles?

to prevent blood flowing backwards

what is the process of the flow of blood through the heart?

blood from the body enters the heart through the vena cava, then it goes to the right atrium, valves stop the blood from flowing backwards, so it goes to the right ventricle, the heart muscles contract so the blood goes to the lungs through the pulmonary artery to be oxygenated, goes back to the heart as oxygenated blood through the pulmonary vein, to left atrium, to the left ventricle, to the body via the aorta

what do red blood cells carry?

oxygen

what do Red blood cells have that allows them to absorb oxygen?

a biconcave disc shape the maximises the surface area

why do red blood cells contain haemoglobin?

it binds to oxygen in the lungs and releases it at the tissues

why don't red blood cells have a nucleus?

so there is more space to carry oxygen

what are the three types of blood vessels?

arteries, veins, capillaries

what do arteries do?

carry blood away from the heart

features of arteries

small lumen, thick outer walls with thick layers of elastic and muscle fibres because they have to carry blood under high pressure

what do veins do?

carry blood to the heart

features of veins

they have a large lumen and thin walls since blood is under low pressure, have valves to stop blood flowing backwards

what do capillaries do?

deliver nutrients to cells and remove waste products from them

features of capillaries

have very thin, permeable walls to allow substances to easily pass into and out of tissues

what are arteries and veins rich in?

arteries are rich in oxygen and glucose, veins are rich in carbon dioxide and waste

what is plasma?

the pale coloured liquid part of blood

what does plasma transport?

hormones, antibodies, nutrients such as glucose, amino acids, minerals and vitamins and waste substances such as carbon dioxide and urea

what do plants need to take in and how are they taken in?

take in water for photosynthesis and minerals for general health, taken in through the roots

what do root hair cells have?

a large surface area to maximise absorption of water and minerals

what is root hair cells membrane like, and how does water and minerals enter them?

membrane is thin which helps absorption, water enters by osmosis, minerals enter by active transport

what three minerals do plants need to be healthy?

nitrates, phosphates, potassium

what are the two types of transport tissue plants have?

xylem and phloem

where are xylem and phloem found?

the stem of the plant

what is translocation?

the movement of sugars (glucose) from the leaf to other parts of the plant by phloem tissue

what does xylem vessels transport?

water and minerals from the soil to other parts of the plant

how are xylem vessel adapted to their function?

they are made of dead cells. they have a thick cell wall and hollow lumen. there are no cell contents and no end cell walls so there is a continuous column for water to move up

what do phloem vessels transport?

the glucose made in the leaf by photosynthesis to other parts of the plant

how are phloem vessels adapted to their function?

they are made of living cells and have lots of mitchrondira to release energy to move substances by active transport

what is transpiration?

the upward flow of water from roots to leaves from where it evaporates into the atomosphere

how do you calculate rate of transpiration?

volume of water lost/time

how can a potometer be used?

to measure water uptake

where is water lost in the leaves?

through stomata

what happens as water is lost from the leaves?

the air bubble moves to the left

how can plants reduce water loss?

they close stomata, but it also reduces the intake of carbon dioxide which will limit photosynthesis

what are the factors that affect water uptake and transpiration?

wind velocity, temperature, humidity

what type of correlation do the graphs have for these factors : wind, temperature and humidity, wind- positive (non-linear) temperature - positive correlation (linear) humidity- negative (linear)