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B4 organising part 4

AQA GCSE B4 organising animals and plants PLANT

QuestionAnswer
Name the organ through which plants absorb water roots
Name the tissue through which water can flow through plants xylem
Name the tissue through which sugar solution can flow through plants phloem
State where photosynthesis takes place in plants leaves
Name specialized cells with containing lots of chloroplasts palissade cells
State the function of chlorophyll absorbs sunlight
Name the cells through which water is absorbed root hair cells
Explain why palisade cells are found at top of leaves Because this is where there is most sunlight, so by having it at the top of leaves, it maximises the amount of sunlight absorbed
Name cells through which gases can diffuse in an out of leaves spongy cells
Give two adaptations of root hair cells Thin cell wall and a long extension of the cell
Explain why root hair cells have a long extension Provides a large surface area (1); to collect more water(1)
Explain why root hair cells have a thin cell wall So that it is easier for water to go through
Would you expect the stomata to be close or open on a hot sunny day? Explain your answer Close to prevent too much water vapour from escaping
Why is the cuticle make of a waxy layer? What is the job of the wax? To prevent water from escaping
State what organelle (part of the cell) would you expect to find in great numbers in the palisade cells? Chloroplasts
Explain why would you expect the spongy cells to contain only a few chloroplast? There is little direct sunlight that reaches the bottom of leaves where chloroplasts are found; so less need to absorb sunlight
Explain why are the palisade cells so tightly packed together? To maximise the amount of sunlight that can be absorbed
Explain why are the spongy cells so loose? To allow air flow more easily
State the mechanism/process by which the gases move from the air space into the spongy cells Diffusion
Explain how diffusion works The gases go from an area of low concentration to an area of high concentration
What is the function of the waxy cuticle? to prevent water loss
What is the function of the palisade cells? they are the cells responsible for photosynthesis. There are lots of chloroplast in a palisade cell.
What is the function of the stomata? It is the hole through which the gas enter
What is the function of the guard cells? they are the cell around the stomata. They will close up or open the stomata to let gases in and out.
How are spongy cells adapted for gas exchange? They are loosely-packed with unusually large intercellular air spaces where gases can collect and mix.
Do you expect leaves with a larger surface area (broad leaves) to lose more or less water? They will lose more water as there are probably more stomata
In a hot climate, would you expect to find more or fewer stomata on leaves? There are probably less stomata PER CM2, so that there is LESS water loss by transpiration
What other advantages are there for a leaf to have a large surface area? Can capture MORE light to produce MORE sugar
Explain why houseplants have more shiny leaves than outdoor plants? In a house, it is hot, so to minimise water loss, the plant will have a thicker cuticle
What is the name of the green pigment found in chloroplast; this pigments absorbs light Chlorophyll
Explain the advantage for plants in the shade to have leaves with a large surface area? to absorb more light
Explain how a palisade cell is adapted to do its job by comparing to a normal cell A palisade cell has MORE chloroplast than a normal plant cell (1) so it can collect MORE ligh (1)
Why is there no starch in a plant that was left for 2 days in the dark? During those 2 days, the plant did not do photosynthesis, so did not make "food". The plant had to use up its store of energy= the plant had to use up the starch
What does a photometer measure? the rate of water uptake
Which tissue transports substances from roots to leaf? xylem
Which tissue transports substances from leaf to roots? phloem
Which tissue transports substances is strengthened by lignin? xylem
Why do plants need water? Plants need water for support. Water makes plant cells turgid (firm) and Plants need water for the process of photosynthesis.
Describe the water movement from roots to leaf Water and dissolved minerals move from cell to cell through the root until they reach xylem vessels .Water move up through the stem to the leaves. Water move into the leaves. Water evaporates from leaf cells and escapes through stomata as water vapour.
What is transpiration? the process in which water leaves the plant by evaporation and diffusion from inside the leaves
What is wilting? when a plant becomes limp or droops because it has lost water and the cells are not turgid anymore.
Name 4 factors that would speed up the rate of transpiration more light, more wind, hotter temperature, less humidity (ie a dry climate)
Where do you find the most stomata? on the bottom of the leaf
What is the role of the stomata? to control the amount of water that goes in and out. Stomata will close to slow the rate of tranpiration.
Why is the rate of transpiration higher on a windy day? The faster the air movement over the leaf, the quicker water vapour is moved away. The concentration of water outside the leaf is kept lower than inside the leaf
Why does the rate of transpiration increase when the light intensity increases? More stomata open as light intensity increases to allow carbon dioxide in for photosynthesis
Why does the rate of transpiration NOT increase anymore after a certain intensity of light? Once all stomata are fully open, the rate of transpiration cannot increase any more
Which tissue is made up of dead tissue? xylem
Which tissue is responsible for translocation? phloem
A group of students wanted to know the mean number of stomata in a leaf.  They used an area of 0.5 mm2 and took several samples. Their counts were: 249, 195, 175, 230, 225, and 205. Calculate the mean number of stomata PER MM2 although the results show a large range, there is no obvious odd result, so the average is 413.1666 but this is for 0.5mm2; so in 1mm2, you need to multiply by 2=426.3; no need to give more than one more significant figures
Plants that are adapted to live in desert conditions, often have no stomata on the upper epidermis. What would be the benefit of this adaptation? reduction in transpiration rate
CHALLENGE: explain why having more stomata on the bottom of the leaf (rather than on top) is an effective survival strategy if the stomata were on top of the leaf, there would be more transpiration as the top of the leaf is hotter
CHALLENGE: why is wilting an important strategy for survival? when the leaf wilts, it does not catch as much light=less photosynthesis= less stomata open; the leaf is closer to teh stem=less surface exposed to wind=less water removed by the wind
Created by: ursulinebio