Topic 2 - Organistation Flashcards
Name 5 plant tissues.
Epidermal tissue Palisade mesophyll Spongy mesophyll Xylem + phloem Meristem tissue (found at tips of roots)
Name three plant organs.
Stem
Leaves
Roots
How is the epidermal tissue adapted to its function?
Waxy cuticle (reduce water loss by evaporation) Upper epidermis is transparent (allows light to pass through to the palisade layer)
How is the palisade layer adapted to its function?
Has lots of chloroplast near top of leaf where they get the most light
How are the xylem and phloem adapted to their functions?
Form a network of vascular bundles (to deliver water, mineral ions and sugar to entire leaf and take away glucose produced by photosynthesis)
Help support structure
How is the spongy mesophyll tissue adapted to its function?
Air spaces to increase rate of diffusion of gases
How is the lower epidermis adapted to its function?
Full of stomata to diffuse CO2
They open and close by using guard cells in response to environmental conditions
What is transpiration?
The loss of water from the plant
What is transpiration caused by?
The evaporation and diffusion of water from a pants surface
What happens in transpiration?
Evaporation creates shortage of water in leaf so more is drawn up via xylem (from the roots)
There is a constant transpiration stream through the plant
What are the four things that effect transpiration rates?
Light intensity
Temperature
Air flow
Humidity
How does light intensity affect transpiration rates?
Brighter light = greater transpiration rates
Stomata close in the dark - photosynthesis can’t happen so stomata don’t need to open and let CO2 in -so little water can escape
How does temperature affect transpiration rates?
Warmer temp = faster transpiration rates
Water particles have more energy when its warm so they evaporate and can diffuse out of the stomata
How does air flow affect the transpiration rate?
Better air flow (strong wind) = greater transpiration rate
If there is little wind then water vapour surrounds leaf and doesn’t move away - high concentration of water particles inside and outside of leaf - so diffusion can’t happen quickly
How does humidity affect transpiration rates?
Drier air = faster transpiration rates
If air is humid there is a lot of water in it already - high concentration of water particles inside and outside of leaf - can’t diffuse quickly
How can you estimate the rate of transpiration?
By measuring the uptake of water
What is translocation?
The process by which the phloem transports food around the leaf
What happens in translocation?
Phloem transport sugars (made in leaves) around rest of plant for immediate use or storage.
It can flow in both directions
What is the phloem made of?
Columns of elongated living cells with small pores in the end walls to allow cell sap to flow through it
What is the function of guard cells?
Open and close stomata
How do guard cells control the stomata when it is filled with water?
the guard cells are filled with it and plump up - the stomata must then open to release this water via evaporation so gases can be exchanged for photosynthesis
How do guard cells control the stomata when it is low on water?
The guard cells have no water and are empty making the stomata close to help stop too much water evaporating
How are guard cells and stomata adapted for gas exchange and water control?
Thin outer walls and thick inner walls
Sensitive to light - close at night
More stomata on underside (no direct sunlight so no excess evaporation happens)
What do cells makeup?
Tissues
What do tissues makeup?
Organs
What do organs make up?
Systems
What do systems make up?
An organism
What is the first stage of the digestive system?
In the mouth
- food is chewed and physically broken down
- enzymes in the salvia then start the chemical reaction
What is stage 2 if the digestive system?
In the oesophagus
- contracts to push food down to stomach
What is stage 3 of the digestive system?
In the stomach
- food is mixed with HCl to kill bacteria (chemical breakdown)
What is stage 4 of the digestive system?
In the liver
- bile is produced to neutralise acids
What is stage 5 of the digestive system?
In the small intestine
- absorbs food into bloodstream via villi (large surface area)
What is stage 6 of the digestive system?
In the large intestine
- excess water is absorbed
What is stage 7 of the digestive system?
In the rectum
- stored as faeces
What are enzymes?
Biological catalysts
What do enzymes do?
Help to control the rate of reaction
What are enzymes made from?
Large protein molecules made up of chains of amino acids folded into certain shapes
What is the shape of an enzyme and its matching substrate called?
Lock and key
How are enzymes denatured?
High temperatures
Wrong pH
What is the active site of an enzyme?
Where the enzyme breaks the substrate down
At what temperature are most enzymes denatured?
40 degrees Celsius
Where is amylase made?
Mouth
Pancreas
Small intestine
What does amylase do?
Breaks down starch into glucose
Where is protease found?
Stomach
Pancreas
Small intestine
What does protease do?
Breaks down proteins to amino acids
Where is lipase made?
Pancreas
Small intestine
What does lipase do?
Breaks down fats into fatty acids and glycerol
Where is bile stored?
Gall bladder
What does bile do?
Neutralises stomachs acid (produces alkaline conditions) Emulsified fats (physical breakdown)
What features of the liver mean that fats can be broken down quicker?
Alkaline conditions
Large surface area of droplets
What are the four parts of the respiratory system?
Lung > bronchus > bronchioles > alveoli
What are alveoli and how big are they?
Air sacs
One cell thick
What is stage 1 of the heart in the circulatory system?
Deoxygenated blood enters heart through vena cava into right atrium
What is stage 2 of the heart in the circulatory system?
The blood is pumped through the tricuspid valve into the right ventricle
What is stage 3 of the heart in the circulatory system?
Blood is pumped through the valve to the lugs via the pulmonary artery
What is stage 4 of the heart in the circulatory system?
Oxygenated blood from lungs enters left atrium from pulmonary vein
What is stage 5 of the heart in the circulatory system?
The blood is pumped through the valve into the left ventricle
What is stage 6 of the heart in the circulatory system?
Blood is pumped out of the aorta to the rest of the body
Why does the left side have thicker walls?
Oxygenated blood
High pressure
More powerful contraction to get blood around body not just to lungs
What are pacemaker cells?
Control heart rate by producing small electrical impulses that cause the heart to contract
Where are pacemaker cells?
Right side of heart
What can be done if pacemaker cells fail?
An artificial pacemaker can be fitted
What is the lumen?
Space where blood flows inside veins, arteries and capillaries
What do arteries do?
Carry high pressure blood away from heart
Why do arteries have thick walls?
Fast speed
What do veins do?
Carry low pressure blood back to heart
Why doe veins have thinner walls?
Less pressure and elasticity
Why do veins have valves?
Prevent back flow
What do capillaries do?
Connect veins and arteries
Why do capillaries have thin walls?
Only one cell thick
Aloe glucose and oxygen to pass through into muscles
Where are red blood cells made?
Bone marrow
What do red blood cells do?
Carry oxygen
How are red blood cells adapted to maximise oxygen diffusion?
Large surface area
Lots of haemoglobin
What do platelets do?
Clot blood to form scabs
What do white blood cells do?
Fight infection
What is plasma?
Straw coloured liquid part of blood that transports CO2, oxygen and takes waste products to kidneys
What causes heart disease?
Layers of cholesterol build up inside arteries and prevent blood flow and increase pressure
How can we reduce cholesterol?
Statins
What do statins do?
Slow down build up or fatty materials by killing cholesterol
What is the negative impact of using statins?
Damages good cholesterol
Not instant
Negative side effects
Long term drug that need to be taken regularly
What is cancer?
Uncontrollable growth and cell division
What are benign tumours?
Doesn’t effect physical health
Not cancerous
What are malignant tumours?
Invade neighbouring cells and spread to form secondary tumours
Cancerous
What are stents?
Tubes that are I stereo into arteries to keep them open
What is an advantage of a stent?
Lower risk of heart attack
Effective for a long time with quick recovery time from surgery
What are the disadvantages of stents?
Complicated surgery
Blood clots can develop near stents - THROMBOSIS
