B5 Flashcards
Explain the process of photosynthesis
Photosynthesis occurs in leaves -> process that manufactures carbs (glucose) from raw materials using energy from light
Leaves -> CO2 from air
Roots -> water from soil
Energy -> light energy from the sun converts CO2+ water -> food-glucose (occurs in chloroplast that has chlorophyll (the part that absorbs light energy))
Photosynthesis produces glucose and oxygen
What is the word equation for photosynthesis?
Carbon dioxide + water -> glucose + oxygen
NEED LIGHT AND CHLOROPHYLL
What is the balanced equation for photosynthesis?
6 CO2 + 6 h2O -> C6H12O6 + 6 O2
IN THE PRESENCE OF LIGHT AND CHLOROPHYLL
What does chlorophyll do?
Chlorophyll -> green pigment in chloroplast which is in plant cells
Sunlight on chlorophyll -> absorb light energy -> released-> helps CO2 and water combine with help of enzymes -> glucose contains energy from (CO2 and H2O reaction)
Light energy -> chemical energy
What are the ways carbs/glucose is used and stored in the body?
Synthesis
Storage
Transport
Respiration
Cellulose
How is glucose used in synthesis?
Glucose + minerals from soil -> compounds
Nitrate ions:
Glucose provides material for protein/cell growth
Magnesium ions:
Glucose + ions -> chlorophyll
How is glucose stored in plants?
Glucose molecules join together -> insoluble starch -> stored until needed
Can be used as energy source (carbs -> lipids) or as nectar
How is glucose used in respiration?
Energy is released from glucose
Used for molecule growth
And food (mostly for animals)
How is glucose used to make cellulose?
100s of glucose molecules join -> rough fibrous carbohydrate material -> used for cell wall
Explain an experiment that shows why light is necessary for photosynthesis
Before experiment:
Plant destarched (prevents starch already there from affecting results) -> dark cupboard for 24 hours
Test leaf for presence of starch
Experiment:
Cover leaf on plant partially with aluminum foil/black paper (make sure it stuck well) -> place in sunlight for one day
After -> test for presence of starch
Result:
Area covered -> orange brown (bc it didn’t receive light and couldn’t photosynthesis)
Area exposed -> blue black (was exposed to light and could photosynthesis)
Explain an experiment that shows why chlorophyll is necessary for photosynthesis
Chlorophyll -> test for starch to see which parts of the leaf are photosynthesising
Experiment:
1. De starch
2. Leave plant in warm+sunny spot
3. Leaf dropped in boiling water (kills cells+breaks down membranes)
4. Leave leaf in hot ethanol for 5-10 min using double boiler (ethanol removes chlorophyll (color change later is easier to see))
5. Left washed/dipped in boiling water
6. Leaf spread onto a white tile
7. Cover in iodine solution
8. entire leaf turns blue-black (bc photosynthesis is happening in whole leaf)
Test for chlorophyll by using a variegated leaf (partially white and green (white parts -> no chlorophyll -> no photosynthesis -> no starch))
Explain an experiment that shows why carbon dioxide is necessary for photosynthesis
Experiment:
1. Destarch 2 plants
2. One plant -> bell jar with sodium hydroxide (absorbs CO2)
3. Second plant -> bell jar with beaker of water (control)
4. Place both in sunlight more several hours
5. Test plants for starch
Results:
Sodium hydroxide plant -> orange brown -> couldn’t photosynthesis without CO2
Water plant -> blue black -> had all requirements for photosynthesis
What could effect the rate of photosynthesis?
Light -> more light, faster photosynthesis -> if light has damaging UV or is too hot -> damage
Carbon dioxide -> more cO2 -> faster photosynthesis
Temp -> enzymes in photosynthesis (chemical reaction requires enzymes) work best at optimum -> nothing above 40°C or they denature
What can be used in an experiment to observe the rate of photosynthesis?
Aquatic plant -> elodea or cabomba
Photosynthesis -> gas released -> if plant is in water oxygen can be seen as bubbles -> # of bubbles/min can show rate of photosynthesis or collect gas in upside down test tube
What experiment can be done to investigate the effect of light intensity on photosynthesis?
Set up:
- Beaker of water (with sodium hydrogencarbonate) with:
Inverted funnel with aquatic plant under it
- test tube over opening of funnel to collect gas
- thermometer to monitor temp
Lamp going through glass tank of water -> distance of lamp changes to observe the rate of photosynthesis
More light more photosynthesis
What experiment can be done to investigate the effect of changing temp on photosynthesis?
Set up:
- Beaker of water (with sodium hydrogencarbonate) with:
Inverted funnel with aquatic plant under it
- test tube over opening of funnel to collect gas
- thermometer to monitor temp
- lamp at constant distance
- hot plate heating from the bottom -> vary temp and observe the changing rate of photosynthesis
Generally more temp more photosynthesis (but not past denature point of enzymes)
What experiment can be done to investigate the effect of changing carbon dioxide on photosynthesis?
Set up:
- Beaker with:
Inverted funnel with aquatic plant under it
- test tube over opening of funnel to collect gas
- thermometer to monitor temp
- lamp at constant distance
water -> varying amounts of sodium hydrogencarbonate solution
More CO2 more photosynthesis
What is a limit factor?
If plant had unlimited resources -> limited by its own ability to absorb and react the materials
Reality -> limiting factor is the material that is the lowest at the time
WATER IS USUALLY NOT CONSIDERED TO BE A POTENTIAL LIMITING FACTOR -> amount needed is less than compared to water transpired
Using a diagram, label the different parts in leaves of dicotyledonous plants.
Chloroplast
Cuticle
Guard cells
Stomata
Upper epidermis
Lowe epidermis
Palisade mesophyll
Spongy mesophyll
Vascular bundles
Xylem
Phloem
What is the functions of: palisade mesophyll
Column shaped cells
Packed and evenly distributed with chloroplast (absorb the most light) -> maximise photosynthesis
What is the functions of: stomata
Where gas exchange takes place
Open during day, closed at night
Where evaporation of water takes place
In greater concentration on the underside of the leaf -> reduce water loss
What is the functions of: spongy mesophyll
Has internal air spaces -> increase surface area: volume ratio for diffusion of gas
What is the functions of: guard cells
Absorb/lose water to open/close the stomata -> allow CO2 in and O2 out
What are the functions of the stomata, spongy mesophyll and guard cells in gas exchange?
Low CO2 -> guard cells are turgid (full of water ) -> curve out
Opens stomata -> gas exchange and evaporation of water
High CO2 -> guard leaf lose water (evaporation) -> flaccid -> stomata closes
Allow for easy movement of gas thorough palisade mesophyll (chlorophyll)
What is the functions of: xylem
Transports water + mineral ions from shoot -> leaves
Made of dead cells
lignin (protein) to strengthen tubes -> support
What is the functions of: phloem
Transports sugar (glucose) produced in leaves -> stem to growing/storage tissue
Living cells -> sieve tubes with small holes in the cell wall -> flow between cells
Why are nitrate ions important?
Nitrate ions + glucose -> amino acids -> protein -> cell growth
Absorbed by root hair cells from soil
Why are magnesium ions important?
Magnesium ions + nitrate ions + glucose -> chlorophyll -> needed for photosynthesis and healthy plant
Absorbed by root hair cells from soil
What is the effect of a nitrate ion deficiency in plants?
Stunted growth (proteins needed for growth)
Yellowing of leaves (nitrates needed for chlorophyll)
What is the effect of a magnesium ion deficiency in plants?
Yellowing between veins of leaves (chlorosis)
-> needed to make chlorophyll
What are some plant adaptation?
Large surface area:
More space for diffusion of gas and absorption of light
Thin:
CO2 diffuses to palisade mesophyll quickly
Chlorophyll:
Absorbs light energy
Network of veins:
Transport of water, carbohydrates
Stomata:
CO2 and O2 can easily diffuse
Epidermis -> thin and transparent:
More light reach palisade cells
Thin cuticle of wax:
Protect leaf without blocking sun
Palisade cell layer on top of leaf:
Maximizes light absorption
Spongy layer:
Air -> diffusion allow CO2 to get through leaf faster (by increasing surface area)
Vascular bundles:
Thick cell wall -> support stem and leaf
What is the function of: wax cuticle
Protective layer on top of leaf
Prevents water from evaporating where it isn’t supposed to
What is the function of: upper epidermis
Thin+transparent -> allows light to enter
What is the function of: lower epidermis
Contains guard cells+stomata
How is glucose transported?
Sugars transported as sucrose
