Plants Flashcards
What is Epidermal Tissue?
Epidermal Tissue covers plants and protects them
What is Palisade Mesophyll?
Palisade Mesophyll contains CHLOROPLASTS for PHOTOSYNTHESIS
What is Spongy Mesophyll?
Spongy Mesophyll contains SOME chloroplasts, but have AIR SPACE for DIFFUSION
What is Xylem?
Xylem carries WATER and DISSOLVED MINERALS from the roots to the leaves
What is Phloem?
Phloem carries DISSOLVED FOOD from the leaves around the plant
What is Meristem Differentiation?
Meristem Differentiation is where the Meristem Tissue DIFFERENTIATES into any tissue the plant needs. It RAPIDLY DIVIDES and is found at the SHOOTS and ROOTS of a plant
Revision notes -
Tissues, such as Palisade, Spongy Mesophyll, Xylem and Phloem are ARRANGED into ORGANS, with SPECIALISED FUNCTIONS
Revision Notes -
The ROOTS, STEM and LEAVES form an ORGAN SYSTEM for the Transport of Substances around the plant
How do plants make their food?
Photosynthesis
What is photosynthesis?
Photosynthesis is a chemical reaction that converts light energy into chemical energy in the form of glucose which provides energy for the organism
What is the WORD equation for photosynthesis?
Carbon Dioxide + Water ——> Glucose + Oxygen
What is the SYMBOL EQUATION for photosynthesis?
6CO2 + 6H20 + (energy) → C6H12O6 + 6O2
What stages are photosynthesis divided into?
- Light dependent
- Light independent
What is an endothermic reaction?
An endothermic reaction means energy is transferred from the surroundings to keep it going
How does CO2 reach the chloroplasts?
CO2 gets to the chloroplasts by going through -
—> Stomata —> Diffusion —> Air space —> Spongy Mesophyll —> Palisade Mesophyll —> Cell Membrane —> Chloroplasts
How is glucose (from photosynthesis) used?
Some of the glucose produced in photosynthesis is used in RESPIRATION , where energy is released by reacting glucose with oxygen
This energy can be used to -
- build other molecules, eg. Cellulose
- making amino acids, (which make proteins for growth and repair)
- making days and oils (to store energy)
Some glucose is converted to insoluble starch for storage as well.
What is the midrib?
The midrib supports the lead in a horizontal position (ie. the big strong vein in the middle of the leaf)
What does the mosaic arrangement of leaves do?
It is the arrangement of leaves on a plant that is best to catch light and avoids shading other leaves
What is the cuticle of a plant?
The cuticle protects the plant from dangers, such as drought, pathogen infection and helps to avoid water loss
What is the upper epidermis?
The upper epidermis is a layer of wax that is clear and allows light to penetrate. Helps to protect the leaf.
What is an adaptation of leaves?
They are very thin, so there is a smaller diffusion distance for gases and light to penetrate
What is stomata?
The stomata is responsible for gas exchange, where it allows gases in and out of the leaf. It is also responsible for regulating water movement through transpiration
What is the word equation for respiration?
Glucose + Oxygen –> Carbon Dioxide + Water + ENERGY
Glucose is combined with another molecule to make amino acids - what is that molecule?
Nitrates
Glucose can be converted to lipids - where are they stored?
Seeds
What sugar is made in Potosynthesis?
GLUCOSE
How can one test for starch?
One can test for starch in an IODINE SOLUTION
What colour does Iodine solution turn into in the presence of starch?
Blue-black
What needs to be done with the chlorophyll before testing for starch in a leaf?
The chlorophyll needs to be removed
What are waste products of Photosynthesis?
Oxygen
What is required in photosynthesis?
CO2, H2O
How can one test for Photosynthesis?
One can test for starch using an Iodine Solution, where the iodine solution turns blue-black if starch is present, and this test for photosynthesis because if starch is present, then photosynthesis has occurred.
What is the initial colour of an Iodine Solution?
Brown
What degrees does Ethanol boil at?
78 degrees C
How do plants make their own food?
Photosynthesis
What does respiration allow the plant to do?
It allows the plant to convert the rest of the glucose produced into other useful substances which can be used to grow
What else is required other than the products of photosynthesis in order to produce substances such as Cellulose or starch?
Minerals from the soil
What can glucose be turned into for storage?
Insoluble starch
Where can starch be stored in a plant?
Roots, leaves, stems
When can glucose be used in plants?
Glucose can be used when PHOTOSYNTHESIS is NOT occurring, eg, (At night or at Winter)
What are two examples of plants that store lots of starch UNDERGROUND?
Carrots and Potatoes
What do carrots and potatoes grow underground for?
So a new plant can grow from it in the following spring once winter is over.
What are we essentially eating when we eat a potato?
The swollen storage organs
What are Lipids
Fats and Oils
What can lipids be used for?
Storage in SEEDS
What can seeds store?
Lipids and Starch
What do Sunflower seeds contain a lot of, and what can we make from them?
Lots of Oil is contained in sunflower seeds, and we can make margarine and sunflower oil from them
What is a Seed?
A Seed is a small embryonic PLANT enclosed in a covering called the seed coat, usually with some stored foods, (Starch of Lipids)
How is food stored in fruits?
Sucrose is used for storage in plants
How Sucrose formed?
Sucrose if formed when one combines Glucose and Fructose
Why do fruits taste nice?
Fruits deliberately taste nice so that animals will eat them to spread the seeds everywhere in excrement
How are cell walls made?
Glucose is converted to CELLULOSE which makes up the Cell Walls
What do cell walls do?
They provide cells with structural support and protection. It is a tough layer that surrounds plant cells.
What do cell walls allow plants to do?
To grow tall without any other support
What is an important function of the cell wall OTHER than structural support?
It acts as a pressure vessel, preventing Over-Expansion when water enters the cell via osmosis
How are proteins made?
Proteins are made when photosynthesis in a plant produces glucose as a product, which is combined with NITRATES and converted into AMINO ACIDS which are made into PROTEINS
What are proteins?
Proteins are the building blocks for life itself
What are Enzymes?
Enzymes are PROTEINS
What do proteins make up?
Organelles within cells, eg. Ribosomes (Which curiously make protein themselves)
Why do Nuts and Seeds contain large amounts of protein?
They need to SUSTAIN the plant in its first few days of life
What is required in photosynthesis?
Carbon Dioxide and Water
What is produced in Photosynthesis?
Oxygen and Glucose
How can one test for Photosynthesis?
One can test for PHOTOSYNTHESIS by using an IODINE SOLUTION to test for STARCH
What is a LIMITING FACTOR?
A limiting factor in Biology can be defined as something present in the environment in such short supply that it restricts life’s processes
What are some examples of limiting factors for photosynthesis?
LIGHT, TEMPERATURE, CO2
How does temperature affect the rate of Photosynthesis?
An increasing temperature catalyses the chemical reaction, where optimal temperature is perfect, however if the temperature exceeds optimal, he enzyme becomes denatured and the rate of reaction decreases
How does Light affect the rate of photosynthesis?
As light is increased, the rate of photosynthesis increases too, so LIGHT IS THE LIMITING FACTOR HERE, however one it reaches the limiting factor of another element, the rate of photosynthesis slows. The other limiting factor could be CO2.
How does CO2 affect the rate of Photosynthesis?
As CO2 is increased, the rate of photosynthesis increases too, so CO2 IS THE LIMITING FACTOR HERE, however one it reaches the limiting factor of another element, the rate of photosynthesis slows. The other limiting factor could be light.
Why are LED lights used when investigating PHOTOSYNTHESIS?
They are used to minimise temperature change in the environment (LEDs don’t release as much heat)
How does one investigate how certain environmental factors change the rate of photosynthesis?
One adds PONDWEED to a SODIUM HYDROGEN CARBONATE solution in a boiling tube, (SHC releases CO2, which is necessary for photosynthesis)
Leave this for 5 mins in order to ACCLIMATISE to the conditions of the boiling tube
Gas will be produced in bubbles, (Product of photosynthesis is OXYGEN)
Count the number of bubbles per minute (find the mean) and reconduct the experiment at different distances from light source.
Record results and plot a graph.
What is a problem with the typical investigation into how environmental factors affect the rate of photosynthesis?
The bubbles don’t always have the same volume of air, and they could be too fast to count
What are solutions for the problems with the typical investigation into how environmental factors affect the rate of photosynthesis?
Use a funnel to see the oxygen produced so the volume can be measured
What is the Inverse Square Law?
If you double the distance the number of bubbles per minute falls by a factor for 4. This causes O2 to fall by 4 times too
Note…
One needs to be able to describe how to investigate the effect of light intensity on photosynthesis, and also explain how these results are affected by the inverse square law.
How is light intensity measured?
By using the INVERSE SQUARE LAW, where light density is equal to 1/(d^2)
What do the 2 transport systems in a plant do?
One carries water and mineral ions from the roots to the rest of the plant, (Xylem) and the other carries the products of photosynthesis from the leaves to the rest of the plant, (Phloem)
What is active transport?
Where dissolved molecules move from an area of lower concentration to a higher concentration, (Across concentration gradient) and requires energy to do so.
What is osmosis?
Diffusion of water across a semi-permeable membrane
What can phloem contain? Where does it go?
Dissolved foods, eg. Sugar
What is the movement of sugar in phloem called?
Translocation
What does Xylem do?
Transports the water and mineral ions from roots up stem to the rest of the plant.
What is formed when xylem and phloem are arranged closely together?
Vascular Bundle
Where in a Transverse Section of a leaf are xylem and phloem arranged?
Xylem on top, phloem on bottom
What else can xylem do for a plant?
Provide support
What is the Transpiration Stream?
The CONSTANT FLOW of WATER taken up from the ROOT through the XYLEM and out of the LEAF through EVAPORATION
What are some adaptations to root hair cells?
High Surface area to maximise the osmosis of water across the membrane
Thin walls for short diffusion distance
Lots of Mitochondria to provide energy for ACTIVE TRANSPORT
Large Vacuole to store solutes
What is a dilate solution?
A dilate solution contains high concentrations of water molecules
What is a concentrated solution?
A solution with a high concentration of solutes but a lower concentration of water molecules
How does osmosis work in terms of a concentration gradient?
It moves DOWN the concentration gradient
What is Transpiration?
The loss of water from the plant’s leaves, where water is pulled from the roots via the xylem in the transpiration pull. Water diffuses across the concentration gradient from the roots via osmosis, and the difference in pressure between the top and bottom of the xylem causes the water to move from the roots to the leaves. Along the way up the transpiration stream, water molecules stick to each other through cohesion, and stick to inside of the xylem vessel through adhesion which aids the mass flow of water up through the plant.
What is Cohesion?
Where water molecules stick to each other
What is Adhesion?
Where water molecules stick to the inside of the xylem vessel
What does the transpiration stream rely on?
Pressure difference between the TOP and BOTTOM of the XYLEM.
Cohesion.
Adhesion.
How do you work out percentage change in an exam?
Change / Initial X 100 = Percentage change
How does stomata benefit the plant?
Allows CO2 in and O2 out, as well as regulating water los, (where stomata closes at night so water isn’t lost)
What happens when water moves into the guard cells?
The cells become TURGID, and when they become turgid, the STOMA OPENS
What happens to stomata at night?
Water moves out of the guard cells by osmosis, and cells become flaccid and the stomata closes
What are the factors that affect transpiration?
- temperature
- humidity
- wind
How does temperature affect transpiration?
Water can evaporate easily, so doesn’t take much energy
How does humidity affect transpiration?
Make the concentration gradient shallower, so transpiration is slower because evaporation is against a shallower concentration gradient.
How does wind affect transpiration?
Increased wind means more water molecules are blown away from the leaf surface so the concentration gradient is increased, so the rate of transpiration is increased.
How does light intensity affect rate of transpiration?
In light intensity caused stomata to open wider so rate of transpiration increased as a result.
Note…
Revise ‘Calculating rate of Transpiration’ investigation
What does a lack of nitrates cause?
Glucose produced in photosynthesis cannot be combined with these nitrates meaning the plant cannot grow, thus a crop cannot profitably grown.
What does a lack of magnesium cause?
A lack of magnesium means the plant cannot produce enough chlorophyll for photosynthesis, resulting in the leaves becoming yellow and the growth slows because the plant cannot photosynthesise fully.
How can a lack of magnesium and a lack of nitrates be healed?
Fertilisers can cure it, however if not treated the plant soon dies.
What can pests do to a plant?
Pests such as aphids can deprive the plant from the products of photosynthesis which it needs to grow. An example of this could be how aphids can prevent them from accessing mineral ions in the soil, meaning that the glucose cannot be converted to useful products due to lack of magnesium or nitrates. This can explain the yellow colour change in the leaves because the Mg ions are limited due to the pests preventing access to the minerals in the soil.
What are tropisms?
Tropisms are a directional growth response, triggered by a stimulus where a plant grows in a certain direction.
Why do plants respond to stimuli?
To avoid stress, to avoid being eaten, to enhance survival and to improve chances of having offspring
What controls growth in plants?
Hormones
What are 3 examples in a plant whose growth is affected by hormones?
Roots and Shoots
Seed Germination
Fruit Ripening
What are the 4 tropisms in plants?
Phototropism - (plants grow in direction of light)
Gravitropism - (plants grow in direction of gravity pull)
Chemotropism - (roots grow towards the chemicals in the ground beneath them)
Hydrotropism - (roots grow towards water)
What is auxin / Where is it found / How does it work in the shoots?
Auxin is a hormone which promotes growth in plants. It can be found in the shoots of the plant. It works when sunlight breaks down the auxin on the side with higher light intensity, so there is more auxin on the shaded side of the plant. As a result, because auxin in shoots causes increased growth, the shaded side grows faster than the side in direct sunlight, meaning the plant will lean in the direction of the sunlight in a process called phototropism, stimulated by light.
What does Auxin do in the roots?
Auxins have the opposite effect naturally in roots to what it does in the shoots. This means that while they still accumulate on the darker side, the hormone causes a decrease in growth, meaning the side with the most direct sunlight will bend downwards and into the ground, and the root grows downwards in a process called gravitropism.
What is Ethene in plants?
Ethene is a hormone which is widely used in the farming industry to control the ripening of fruits.
Give one other use of Auxins. (other than growth)
It can be used as an effective weed killer by causing rapid, uncontrolled growth which kills the weed.
What is gibberellin in plants?
Used in the brewing industry to end seed dormancy.
They are used to promote flowering throughout the year, especially in pot plants such as Pelargoniums.
It is also widely used to increase the size of fruit. Eg. Seedless grapes would be very small due to the fact that seeds produce gibberellins to make the fruit grow. Therefore commercial growers spray the seedling fruit with gibberellins to replace the natural hormone which makes them grow well.
