biology topic 2 (triple content) year 10

what are root hair cells

1. enlarged epidermis cells with large surface : volume ratio = that absorb water and mineral ions

2. have transport proteins in cell membranes to allow mineral ions to be absorbed by active transport

3. exchange substances with soil

how is water absorbed by root hair cells

1. water is absorbed into the roots by osmosis = due to the high concentration of minerals in the root cell

2. water is drawn into the cell from a high water potential in the soil to a low water potential in the cell

3. the root hair cells are on the outer layer and help greatly increase the surface area for osmosis

why do stomata open and close

to allow water vapour and gas to pass in and out of the leaf

what happens when stomata are closed

they conserve water and prevent wilting

what happens when stomata are turgid = open

gas exchange occurs = CO2/O2/H2O

water loss

what happens when stomata are flaccid = closed

prevents wilting

photosynthesis and respiration take place

what is transpiration

the loss of water vapour by evaporation from the stomata

what is the transpiration stream = how water moves from the soil to the xylem vessel

1. water enters root hairs by osmosis

2. water passes up xylem to stem and leaves = due to transpiration

3. if leaf is photosynthesising then water is lost through stomata

how is the rate of transpiration affected by light intensity

1. as light intensity increases = more stomata open = at the top of the leaf = for photosynthesis

2. so more transpiration occurs

3. eventually all stomata will open so any more increase of light intensity will not effect the rate of transpiration

how is the rate of transpiration affected by wind speed

1. as wind speed increases it moves away the water particles surrounding the leaf

2. increasing the water diffusion gradient between inside and outside the leaf

3. increasing the rate of transpiration

how is the rate of transpiration affected by temperature

1. the higher the temperature the more kinetic energy the water particles have = the faster they move

2. they will evporate and diffuse from the surface of the leaf faster

3. increasing the rate of transpiration

how is the rate of transpiration affected by humidity

1. the more humid the air the more water is in it

2. reducing the water concentration gradient between inside and outside the leaf

3. as humidity increases the rate of transpiration decreases

diagram of the potometer + what happens at each step

1. H2O exits the stomata via transpiration

2. H2O lost from the stomata is replaced by the cut stem = it draws more up from the potometer

3. the air bubble moves to the left as the stem draws more H2O from the potometer = the air bubble starts at 0mm on the ruler

4. measure the front of the bubble = see how far it has moved during the certain length of time

what can the pototmeter be used for

to measure the rate of transpiration = as it measures how far the bubble moves in a set time = in different conditions = with the further the bubble moves the faster the transpiration

method for the practical using the potometer to find the rate of transpiration in hot and cold air

1. choose time for how long you are going to measure for

2. set air as either hot or cold

3. measure how far the bubble moves as you remove the leaves one by one

4. then do the same with the other temperature

conclusion for the practical using the potometer to find the rate of transpiration in hot and cold air

the more leaves there are the more transpiring the plant does = due to the decrease in leaves mean less stomata

hot air increases transpiration = due to it making the plant hot = creating less moisture in the air = forcing the plant to transpire

what are antibodies

proteins that recognise and bind to antigens

what are antigens

a protein on a foreign object that stimulates the immune system to produce antibodies

what are antitoxin

white blood cells produce them

what are antibiotics

this substance is used to kill bacteria

what are painkillers

this substance relieves only symptoms of a disease

what is the role of a antigen

1. when a new pathogen enters the body

2. it introduces a new antigen

3. for every new antigen, our lymphocytes build a specific antibody

4. this will have a complementry shape to the antigen so the antigen will bind to the pathogen and destroy it

what is a vaccine + its role

the administration of a weak or dead pathogen = provide long term immunity and help control the spread of disease

role =

1. harmless pathogen is given which has antigens on the surface

2. antigens trigger an immune response

3. lymphocytes produce antibodies to kill the pathogen and release antibodies which bind to antigens to destroy the pathogens by either 1. killing them directly 2. labelling them so phagocytes engulf them 3. neutralise their toxins 4. cause them to burst

4. some lymphocytes remain in the blood as memory cells which help give long term immunity by killing future pathogens by releasing antibodies when required

5. should the pathogen be encountered again the body responds by rapidly releasing thousands of antibodies = this should help with long term immunity + controlling the spread of disease

what 3 things does the MMR vaccine protect children against

1. measles

2. mumps

3. rubella

what are the two things platelets help prevent in the clotting process

1. pathogen entry into the blood

2. blood loss

what do platelets use to convert the soluble protein fibrinogen into the insoluble protein fibrin which forms the clot (scab)

platelets use calcium

why is blood clotting important

1. prevents significant blood loss from wounds

2. scab formation seals the wound with an insoluble patch to prevent entry of microorganisms

3. remains in place till new skin is grown which seals the skin again

What are the 4 things that make up the urinary system

1. Kidneys

2. Ureters

3. Bladder

4. Uretha

What does the urethra contain + what that does

The urethra contains two ring shaped muscles = sphincter muscles

They can contract to close the urethra + to hold back the urine

Label the parts of the kidney + what are the 6 parts of a kidney

1. Cortex

2. Medulla

3. Pelvis

4. Ureter

5. Renal vein

6. Renal artery

What is the function of the cortex

Where blood is filtered + contains nephrons

What is the function of the medulla

Where the concentration of urine is determined

What is the function of the nephron

Form the basic units of the kidney

What is the function of the ureter + what is it

Carries urine to the bladder + tube that leads kidneys to bladder

What is the function of the renal artery + renal vein

Empty urine into the pelvis from the pyramids

Label the nephron tube

What happens in the bowman’s capsule

Ultrafiltration = tiny pores allow the glomerus filtrate to pass through + small substances are forced out of the blood + filtered by the bowman’s capsule into the nephron

What happens in the glomerulus

Blood from the renal artery = under high pressure = forces small substances (glucose, urea, ions, water) out into the glomerus that sits in the bowman’s capsule = as blood flows out of it fluid called = glometer filtrate = is forced out through pores into the bowman’s capsule

What are used in selective re absorption

PCT = proximal convoluted tubule

Loop of Henle

What happens in the PCT = proximal convoluted tubule

100% of glucose is reabsorbed into the blood via active transport

What happens in the loop of henle + what how much reabsorptionn depends on

Re absorption of salts and water = how much re absorption happens depends on hydration, diet and activity

What happens in the DCT = distial convuluted tubule and the collecting duct

Adjusts levels of water in the blood

1. Osmoreseptors in the brain detect high or low water levels in the blood

2. The pituitary glands (in the brain) responds by increasing or decreasing the release of ADH

3. ADH makes the DCT and the collecting duct more permeable to the water (causing reabsorbtion of more water in the blood) = osmoregulation

How does the levels of water affect ADH

High water = more ADH

Low water = less ADH

What is urine made out of

A solution of water, urea and ions

What is excretion

Removal of cellular / metabolic waste

What is osmoregulation

Regulating water levels of the blood

Why cant protein pass through the glomerculus but glucose can

Because protein is a large molecule and glucose is small nenough to pass through

How is water reabsorbed from the collecting duct + Why does selective re absorption of glucose happen in the proximal convultuted tubule

1. All glucose in the proximal convoluted tubule by active transport

2. As filtrate drips through the loop of henle = sufficient salts are reabsorbed back into the blood by diffusion and water follows by osmosis

3. Sufficient water is also reabsorbed from the collecting duct depending on how much the body needs

What is the effect of ADH + where it comes from + what it affects

Secretes many different hormones = from the pituitary gland + effects osmoregulation

What is the effect of LH + where it comes from + what it affects

Secretes many different hormones = from the pituitary gland + affects the ovulation and release of eggs

What is the effect of FSH + where it comes from + what it affects

Secretes many different hormones = from the pituitary gland + effects the growth of follicle