Quick Review Flashcards - Click to flip and test your knowledge!
Question
What is the process by which green plants synthesise food from $CO_{2}$ and water using light energy?
Answer
Photosynthesis
Question
Organisms that prepare their own food from basic raw materials are known as _____.
Answer
Autotrophs
Question
Why is photosynthesis considered the most significant life process for animal life?
Answer
It provides food and releases free oxygen into the atmosphere.
Question
Which green pigment is essential for trapping light energy during photosynthesis?
Answer
Chlorophyll
Question
In which microscopic plant cell organelles is chlorophyll contained?
Answer
Chloroplasts
Question
What are the closely packed flattened sacs found inside a chloroplast called?
Answer
Thylakoids
Question
A pile of thylakoids within a chloroplast is referred to as a _____.
Answer
Granum
Question
What is the colourless ground substance inside a chloroplast called?
Answer
Stroma
Question
Which mineral element is a core component of the complex chemical substance chlorophyll?
Answer
Magnesium
Question
The two most abundant and well-known types of chlorophyll are chlorophyll-a and _____.
Answer
Chlorophyll-b
Question
Which specific colours of the visible light spectrum are most effective for photosynthesis?
Answer
Blue and red light
Question
Why do leaves appear green to the human eye?
Answer
Chlorophyll reflects green light while absorbing other colours.
Question
What occurs to the grass under a stone that results in it turning yellowish?
Answer
Disintegration of old chlorophyll and non-formation of new chlorophyll due to lack of light.
Question
What are the minute openings on the lower surface of a leaf that allow $CO_{2}$ to enter?
Answer
Stomata
Question
Which specific cells regulate the opening and closing of the stomatal pore?
Answer
Guard cells
Question
How does the wall thickness of a guard cell differ between the side facing the pore and the opposite side?
Answer
The inner wall facing the pore is thick, while the outer wall is thin.
Question
According to the $K^{+}$ ion concentration theory, what causes water to be drawn into guard cells during the day?
Answer
Increased $K^{+}$ concentration makes the cells hypertonic.
Question
What is the state of guard cells when the stomatal pore is open?
Answer
Turgid
Question
What is the state of guard cells when the stomatal pore is closed?
Answer
Flaccid
Question
In the older sugar concentration theory, what increases the osmotic pressure in guard cells during daytime?
Answer
The production of glucose through photosynthesis.
Question
Why is transpiration often described as 'the price which the plant pays for photosynthesis'?
Answer
Stomata must open for $CO_{2}$ diffusion, which inevitably allows water vapour to escape.
Question
Provide the balanced chemical equation representing the overall process of photosynthesis.
Answer
$6CO_{2} + 12H_{2}O \xrightarrow{\text{light energy/chlorophyll}} C_{6}H_{12}O_{6} + 6H_{2}O + 6O_{2} \uparrow$
Question
Which two types of mesophyll cells are the primary centres for photosynthesis in a leaf?
Answer
Palisade cells and spongy cells
Question
By what mechanism does $CO_{2}$ enter the leaf from the atmosphere?
Answer
Diffusion down a concentration gradient through the stomata.
Question
What are the two main phases of photosynthesis?
Answer
The light-dependent phase and the light-independent phase.
Question
Where specifically within the chloroplast does the light-dependent reaction take place?
Answer
Thylakoids (grana)
Question
What is the smallest unit of light energy absorbed by chlorophyll during activation?
Answer
Photon
Question
Define the process of photolysis in the context of the light reaction.
Answer
The splitting of $H_{2}O$ molecules into hydrogen ions, electrons, and oxygen using light energy.
Question
Provide the chemical equation for the photolysis of water.
Answer
$2H_{2}O \xrightarrow{\text{energy of 4 photons}} 4H^{+} + 4e^{-} + O_{2}$
Question
What happens to the oxygen produced during the photolysis of water?
Answer
It is given out as molecular oxygen ($O_{2}$) or used in respiration.
Question
Which compound picks up hydrogen ions during the light reaction to form $NADPH$?
Answer
$NADP^{+}$ (Nicotinamide adenine dinucleotide phosphate)
Question
What is the process of converting $ADP$ to $ATP$ using light energy called?
Answer
Photophosphorylation
Question
Where does the light-independent (dark) phase of photosynthesis occur?
Answer
Stroma
Question
What is the primary function of the dark phase in photosynthesis?
Answer
The reduction of $CO_{2}$ to form glucose using $ATP$ and $NADPH$.
Question
The term 'dark phase' does not mean it occurs at night; it means the reactions are _____.
Answer
Light-independent
Question
What is the process of converting several glucose molecules into a starch molecule called?
Answer
Polymerisation
Question
In what form is food typically transported through the phloem to different parts of the plant?
Answer
Sucrose
Question
Why is glucose converted to starch for temporary storage in leaves?
Answer
Starch is insoluble and does not affect osmotic pressure.
Question
List three end-products of the photosynthesis process.
Answer
Glucose ($C_{6}H_{12}O_{6}$), water, and oxygen.
Question
How does an extensive vein system in a leaf adapt it for photosynthesis?
Answer
It allows for rapid transport to and from the mesophyll cells.
Question
What is the 'optimum temperature' for the maximum rate of photosynthesis?
Answer
$35^{\circ}C$
Question
What happens to the enzymes involved in photosynthesis when temperatures exceed $40^{\circ}C$?
Answer
The enzymes are destroyed, and the rate of photosynthesis stops.
Question
At what concentration of $CO_{2}$ does the rate of photosynthesis typically stabilise, provided light is constant?
Answer
$0.02\%$
Question
Why does a deficiency in minerals like magnesium lead to a drop in the rate of photosynthesis?
Answer
It causes a loss of chlorophyll, reducing the plant's ability to trap solar energy.
Question
What is the purpose of 'destarching' a plant before an experiment on photosynthesis?
Answer
To ensure that any starch found in the leaves after the experiment was produced during the experiment.
Question
How is a plant typically destarched?
Answer
By placing it in the dark for 24 to 48 hours.
Question
In the iodine test for starch, what colour indicates a positive result?
Answer
Blue-black
Question
Why is a leaf boiled in methylated spirit over a water bath during a starch test?
Answer
To remove the chlorophyll so the colour change can be seen clearly.
Question
What chemical is used in experiments to absorb $CO_{2}$ from the air in a flask?
Answer
Potassium hydroxide ($KOH$)
Question
Which aquatic plant is commonly used to demonstrate the release of oxygen during photosynthesis?
Answer
Hydrilla (or Elodea)
Question
What is the 'starting point' of every food chain?
Answer
A plant (producer)
Question
In a food chain, what term describes animals that eat plants directly?
Answer
Herbivores (Primary consumers)
Question
According to scientists, how long ago did free oxygen first appear in the atmosphere due to photosynthesis?
Answer
About 2 billion years ago.
Question
The series of chemical reactions where carbon is removed from and eventually returned to the air is the _____.
Answer
Carbon cycle
Question
By what process do all plants and animals release $CO_{2}$ back into the atmosphere from their cells?
Answer
Respiration
Question
How do decomposers like bacteria and fungi contribute to the carbon cycle?
Answer
They break down dead organic matter, releasing $CO_{2}$ back into the atmosphere.
Question
What occurs when wood or fossil fuels are burnt, releasing $CO_{2}$?
Answer
Combustion
Question
Which industrial process involving limestone contributes to the release of $CO_{2}$ into the atmosphere?
Answer
Heating (or burning) limestone in lime kilns.
Question
What is the effect of 'too much' light on chlorophyll?
Answer
High intensity light may destroy chlorophyll.
Question
In the context of stomatal movement, what is 'endosmosis'?
Answer
The movement of water into the guard cells from neighbouring cells.