This page contains the AQA GCSE Biology B8 Photosynthesis Questions and kerboodle answers for revision and understanding .This page also contains the link to the notes and video for the revision of this topic.
1. a) The plant gets the carbon dioxide from the surrounding air which consist of different gases(Nitrogen, Oxygen, Carbon dioxide etc) to form Glucose and gets the water from the soil.
b).Algae are the aquatic (that lives in water) organisms and they absorb carbon dioxide dissolved in the water around them and get the light from the sun which they need for the process of Photosynthesis. In this way algae get the carbon dioxide, water, and light they need for photosynthesis
2. The path taken by a carbon atom as it moves from being part of the carbon dioxide in the air to being part of a starch molecule in a plant. In photosynthesis, energy is transferred from the environment to the chloroplasts by light. This energy is then transferred to convert carbon dioxide (CO2) from the air, plus water (H2O) from the soil into a simple sugar called glucose (C6H12O6). The chemical reaction also produces oxygen gas (O2) as a by-product.
6CO2 + 6H2O + energy –> C6H12O6 +6O2
Carbon dioxide + Water + energy–> Glucose+ Oxygen
Some of the glucose produced during photosynthesis is used immediately by the plant cells for respiration and the remaining glucose is converted into insoluble starch and stored.
3. A leaf kept in the light for 24 hours will turn an iodine solution blue-black, whereas a leaf kept in the light for 24 hours and then in the dark for 24 hours will have no effect on an iodine solution because the most important factor for photosynthesis is light. The rate of photosynthesis depends on the quantity and quality of light. The rate of photosynthesis is the maximum in the presence of red and blue lights, while in green light the rate is minimum because green light is reflected by the chlorophyll molecules.
The leaf kept in the light for 24 hours turns an iodine solution blue-black because of the presence of starch and the leaf kept in dark for 24 hours did not receive light, photosynthesis did not occur. Hence no starch was formed there so will have no effect on an iodine solution.
4. a) The word equation that can be used to describe the equation of photosynthesisis
Carbon dioxide + Water + energy–> Glucose+ Oxygen
b) Photosynthesis is an endothermic reaction because these reactions are the reactions in which energy is required from outside Environment.
Photosynthesis is an endothermic reaction because the energy required to break the bonds in H2O+CO2 is more than the energy released by formation of bonds of C6H12O6. The extra energy required for the reaction to take place is transferred from the environment by light.
1) Three main limiting factors that affect the rate of photosynthesis in a plant. Light is directly proportional to the rate of photosynthesis that means more the light more the photosynthesis will takes place and in case of absence of light no photosynthesis will takes place
Temperature is also directly proportional to the rate of photosynthesis. As temperature rises, the rate of photosynthesis increases too.
Carbon dioxide is essential for plants to make Glucose. Increase in carbon dioxide concentration increases the rate of photosynthesis.
2) a) The rate of photosynthesis increases linearly with increasing light intensity (from point A to B on the graph).
b) At a certain light intensity the rate of photosynthesis stay constant (from point B to C on the graph). Here a rise in light intensity has no affect on the rate of photosynthesis as the other factors such as temperature and carbon dioxide become limiting.
c)
In figure 2 after attaining the temperatures above 40°C the rate of photosynthesis slows down. This is because the enzymes involved in the chemical reactions of photosynthesis are temperature sensitive and destroyed at higher temperatures. So it falls down immediately. Where in case of figure 1 and 2 the rate of photosynthesis stay constant.
1 Three ways that a plant uses the glucose produced by photosynthesis:
2 a Starch is found in the cell all over a plant but starch stored in the cells of the leaves. In some plant starch has a special storage area in a plant. For example: in many plants such as potato and onion where starch is store in tubers and bulbs.
b Some of the glucose made by photosynthesis is converted to starch because Glucose made by photosynthesis is converted to starch because starch is reserve food material of plant it provide energy to cells because glucose cannot be stored. Glucose is soluble in water due to this if we store the glucose in plant then could affect the movement of water into and out of cell by osmosis.
If a lots of glucose stored in the plant cells could affect the water balance of whole plant
c Demonstrating that a potato is a store of starch. A chemical test for starch is to add iodine solution (red) and see if it turns blue/black in colour. It is possible to distinguish starch from other carbohydrates using this iodine solution test. For example, if iodine is added to a peeled potato then it will turn black.
3 The two leaves look so different because presence of starch in a leaf
Experiment for starch:
Take a leaf from a plant kept in the light and a plant kept in the dark for at least 24 hours. Just adding iodine solution to a leaf does not work, because the waterproof cuticle keeps the iodine out. Leaves have to be specially prepared so the iodine solution can reach the cell and react with any starch stored there. Also, the green chlorophyll would mask any colour changes if the iodine did react with the starch. You therefore need to treat the leaves by boiling them in ethanol, to destroy the waxy cuticle and then remove the colour. The leaves are then rinsed in hot water to soften them. After treating the leaves, add iodine solution to them both, iodine solution turn blue black in the presence of starch. The leaf that has been in the light will turn blue black. The iodine solution on the leaf kept in the dark remain orange-red
4 Pitcher plants, sundews, and Venus fly traps are often found growing in bogs globally, an environment where not many other plants can survive:
1 The main differences between garden green house and a hydroponics growing system. Both need sunlamps, both are indoors, both need heating. But in hydroponics are just a replacement for soil.
(b) The main benefits of artificially manipulating the environment in which food plant are grown. There is a better crop quality (bigger, less impurities) Quicker crop growth; so food price is decreased as there is more food available.
The one factor that is most likely to be limiting photosynthesis is limited: a. Field of wheat first thing in the morning.- this could be both temperature & light. Morning light is at a low angle and the day is cooler at dawn.
b. The same field later on in the day – If the ground is hot & dry so the plants risk wilting and the stomata close then the CO2 could be limiting. Even if the plant has open stomata barley is a C3 so as the temperature increases so does the rate of carbon lost to photorespiration. If the temperature is over 30C only a fraction of the CO2 taken in can enter the Calvin cycle with the rest lost to photorespiration. Temperature & CO2 are limited
c. Plants growing on a woodland floor in winter. – Temperature
d. Plants growing on a woodland floor in summer. – Light
1 a) carbon dioxide + water —> glucose + oxygen + water
If we balance the equation, we get : 6CO2 + 6H2O —> C6H12O6 + 6O2.
b i) Light for photosynthesis in the geranium come from the sun, in form of sunlight, that is absorbed by the leaves.
ii) Sunlight is absorbed by Leaves, in which a pigment is present called as chlorophyll, inside chloroplasts. There are two types of chlorophyll present in chloroplasts, Chlorophyll a and chlorophyll b that are used to absorb light with red and blue wavelengths.
c) On a cold morning the rate of photosynthesis in the geranium plant is very slow. There are limiting factors that can slow down photosynthesis process are: Concentration of carbon dioxide, intensity if light and temperature.
Light intensity
No matter how much water and carbon dioxide is present, without light plant can’t do photosynthesis. When intensity of light increases, rate of photosynthesis also increases.
Carbon dioxide concentration
Occasionally photosynthesis is limited by the amount of carbon dioxide in environment.
Temperature
Extreme temperatures limit the photosynthesis, high or low temperature decreases the rate of photosynthesis.
d) Some of the glucose produced by the geranium plant is used for respiration.
In three ways glucose can be used:
e) Plants grown in pure water will die, even if they are supplied with light, carbon dioxide, and a growing temperature of around 20°C because pure water is aggressive to dissolve anything it comes into contact with and same is in the case of plants grown in pure water . Some of the things are good, and some are bad. What actually happens to your particular plants depends on a variety of factors.
2) The figures in Table 1 show the mean growth of two sets of oak seedlings. One set was grown in 85% full sunlight and the other set in only 35% full sunlight.
a) Graph showing that the growth of both sets of oak seedlings.
b) Light energy is needed for photosynthesis, so as the light intensity increases, the rate of photosynthesis chemical reactions steadily increases in a linear manner. The more photons of light that fall on a leaf, the greater the number of chlorophyll molecules that are ionized and the more ATP and NADPH are generated so the oak seedlings getting more sunlight grows faster as comparison to the one getting lesser sunlight.
3) a) Plants make food in their leaves. The leaves contain a pigment called chlorophyll, which colors the leaves green. Chlorophyll can make food the plant can use from carbon dioxide, water, nutrients, and energy from sunlight.
b) In plants, water is absorbed through the roots which rises to the leaves and enters special cells called chloroplasts. These cells contain chlorophyll, a green pigment that gives leaves their color by reflecting green wavelengths. More importantly, chlorophyll absorbs light in the red and blue parts of the spectrum and uses it to power a crucial chemical reaction.
c) Demonstrating that photosynthesis take place in the leaves of a plant by Starch Test
Iodine is a purple colored reagent used to test the presence or absence of starch in the leaf conducted for photosynthesis process. In the presence of starch iodine solution will turn into blue-black color and in the absence of starch iodine added to leaf will turn into brown color.
In this experimental leaf, the part of the variegated leaf which contain green patches will give a positive test for starch i.e. iodine when added to this part of the leaf will turn into blue-black color. The reason for this is, this part of the experimental leaf containing green patches include chlorophyll and thus prepare starch through photosynthesis. Thus iodine added to this region will turn into blue-back color. But colored patches of variegated leaf doesn’t include chlorophyll and thus don’t prepare starch through photosynthesis. So iodine added in this region will change into brown color. Thus this experiment proves chlorophyll is necessary for leaves to prepare starch through photosynthesis.
4) a) Oil palms can grow rapidly in the conditions that support a tropical rainforest because it is a typical tree crop of the tropical rainforest. It can however hardly survive or regenerate in dense secondary forest because of the lack of sunshine. This is also the reason why stand-alone trees in villages are generally much taller than in palm groves.
For optimal growth and production the tree requires stable climatic conditions, in particular with respect to light and moisture supply . Any deviation from these conditions enhances a yield decrease.
For optimal growth and production the crop requires a high and year round rainfall with little or no dry season and stable high temperatures; soils should be deep and well drained.
b) The pulp (mesocarp) around the nut contains the red palm oil. The kernel in the nut contains oil very similar to coconut oil, but palm oil and palm kernel oil are chemically different. The palm kernel, the nut found in the centre of each piece of fruit, is extracted and sent to a palm kernel crushing mill. The oil is extracted from the kernel. The pulp left over from this process is pressed together, forming palm kernel cake or expeller. These processes extract three major palm products: crude palm oil, crude palm kernel oil and palm kernel expeller.
c) The energy stored for embryo development before it can start making their own food by photosynthesis.
d) In plants Glucose can be converted into chemicals required for growth of plant cells such as cellulose, can be converted into starch, a storage molecule, that can be converted back to glucose when the plant requires it and also it can be broken down during the process of respiration, releasing energy stored in the glucose molecules.
5) a) Hydroponically-grown plants grow more quickly than soil-grown plants because they have food and water available to them all the time. This means they don’t need a large root system to find nutrients and water and can devote more energy to producing their crop which results in the plant maturing more quickly so rhe yields are always higher.
b) Crops that would be most economically sensible to grow hydroponically are:
Cherry tomatoes do exceptionally well when grown hydroponically. Because they don’t take nearly as long to ripen as their larger counterparts, they provide home growers with fairly quick gratification. Many people who live in northern climates grow cherry tomatoes indoors all year long.
Lettuce is another crop that is easily grown using hydroponic techniques. In fact, many commercial growers are finding this to be much more cost effective than growing lettuce in the traditional way.
Culinary herbs are also easy to grow using hydroponics, particularly since many home cooks prefer to use the juveniles versions of these plants. One small pot of chives, for instance, can keep producing enough vegetative material on a regular basis to meet the needs of most average families. Because there is no need to use herbicides or pesticides in indoor environments, the products of hydroponic gardens are clean and pure.
c) Wheat and Cabbage be least sensible to grow hydroponically? Explain your choice.
d) i) Benefits of the natural environment
Problems:
ii) Benefits of an artificially manipulated environment:
Problems of an artificially manipulated environment:
01.1The chemical equation for photosynthesis is Water +carbon dioxide–> glucose+ oxygen
01.2 The chemical symbol for glucose is C6H12O6
01.3 Photosynthesis is an endothermic reaction. Photosynthesis is considered an endothermic reaction because plants gets the energy to convert carbon dioxide and water into glucose and oxygen from the outside (Sun) environment.
01.4 Photosynthesis in plants is essential for the survival of animals because
plants take the light from sun and use it to make their own food. In the process they use carbon dioxide and light to make sugar (glucose) and oxygen. This benefits other animals that utilize this oxygen and the plants for food.
02.1 The gas used in photosynthesis is Oxygen
02.2 The funnel is supported on pieces of plasticine to raise the funnel.
02.3 The apparatus used to measure the rate of photosynthesis: When placed closer to a light source, the rate of bubbling will speed up, and as the pondweed is taken further away, the bubbles will slow down again – an instant and visual indicator of the importance of light intensity in photosynthesis. The bubbles can be counted and the rate of bubbling can serve as an indication of the rate of photosynthesis, or the gas can be collected in a pipette or microsyringe and the amount measured.
02.4 Three factors that could affect the rate of photosynthesis are:
Light Intensity = Power/Area
03 Steps to test the presence of starch in leaf:
Step 1 Put the leaf in boiling water for 1 minute to soften the leaves.
The leaf was flaccid (soft) after being boiled in water
Step 2 Transfer the leaf into boiling ethanol for 5 minutes to destroy the waxy cuticle and then to remove the colour the ethanol changed from colorless to green
Step 3 Wash the leaf in hot water to soften them again.
Step 4 Spread the leaf on a white tile and cover it with iodine solution. Iodine solution turns blue black in the presence of starch .No colour changes in case of absence of starch
03.2 Safety precautions when you transfer the leaf into boiling ethanol :Put on your eye protection.Add enough ethanol to cover the leaf, and stand the boiling tube in your beaker of hot water, or in the hot water bath.
03.3 Test for presence of starch in leaf : Green parts containing chlorophyll- stained black – starch is present. Light parts of plant with no chlorophyll the iodine remains orange – no starch present.
Conclusion: Chlorophyll must be present in leaf cells for photosynthesis to occur.
04 This is the procedure by which plants make starch from simple raw materials
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This page contains the detailed and easy notes for AQA GCSE Biology Bioenergetic for revision and understanding Bioenergetic.
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It is the process by which green plants prepare their own food by using water, carbon dioxide in presence of sunlight to form glucose and oxygen.
Mesophyll – Photosynthetic cells lies parallel to the surface to absorb maximum light and are closed to the stomata for quick diffusion of gases.
Chloroplast – They have chloroplast which contains chlorophyll and traps light for photosynthesis
Guard cell – They have stomata which are the pores for gas exchange
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As the pH increases the rate increases upto optimum. Beyond optimum the rate decreases as enzymes get denatured.
GLUCOSE
STARCH
CELLULOSE
PROTEINS
LIPIDS
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It is the process of breaking down food to release energy.
AEROBIC RESPIRATION
ANAEROBIC RESPIRATION
PLANTS
ANIMALS
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| BREATHING | RESPIRATION |
| It is a physical process. | It is chemical process. |
| Does not involve enzyme | Involve Enzymes |
| It is breathing in oxygen and breathing out carbon dioxide | It is breaking of food in presence of oxygen for energy |
| No energy is released | Energy is released |
| Takes place outside the cells | Takes place inside the cells |
EXOTHERMIC
As it releases heat.
The energy released in making carbon dioxide and water is more than the energy taken in to break glucose and oxygen
Cristae are the folding of the inner membrane of the mitochondria to increase the surface area for the attachment of the enzymes
MOVEMENT
TRANSPORT
THERMOREGULATION
CATABOLISM
ANABOLISM
Demand for oxygen and glucose increases as more energy is needed
BREATHING RATE
HEART RATE
GLYCOGENOLYSIS
Extra Oxygen needed by the body after exercise to recover.
OXYGEN DЕВТ*
METABOLISM
It is the sum of all the reactions of the body
CATABOLISM
Breakdown reaction in which bigger molecule is broken down into smaller ones.
ANABOLISM
It is the synthesis reaction in which bigger molecule js formed from the smaller ones.
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DETOXIFICATION
BREAKDOWN OF BLOOD CELLS
BREAKDOWN OF HARMFUL SUBSTANCES FOR EXCRETION
BREAK DOWN OF LACTIC ACID
| PHOTOSYNTHESIS | RESPIRATION |
| Only in plant cells | Occurs in all living cells |
| It is endothermic reaction | It is exothermic reaction. |
| Oxygen is produced | Oxygen is used up |
| Takes place in chloroplast | Takes place in Mitochondria |
| Anabolic reaction, glucose is made | Catabolic reaction, glucose is broken down. |
| Light dependent | Light independent |
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Photosynthesis – It is the process by which green plants prepare their own food carbon dioxide and water are combined to form glucose and oxygen in presence of sunlight
Respiration – breakdown of food to release energy
Limiting Factors — Factor that limits the rate of photosynthesis
Endothermic Reaction— Reaction that takes in heat
Exothermic Reaction — Reaction that releases heat
Glucose — product of photosynthesis and fuel for respiration
Starch — Storage carbohydrate in plants
Glycogen — Storage carbohydrate in animals
Aerobic Respiration – Breaking down of food in presence of oxygen
Anaerboic Respiration – breaking down of food in absence of oxygen
Fermentation – Anaerobic respiration in plants that produces ethanol and carbon dioxide
Greenhouse – A glass or a plastic house to control the limiting factors and increase the rate of photosynthesis.
Metabolism – Sum Of all the catabolic and anabolic reactions of the body.
Liver – An organ involved in metabolism.
Lactic Acid — The product of anaerobic respiration in animals
Oxygen Debt —The extra oxygen needed exercise to break down lactic acid and recover to pre exercise state.
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I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.
References:
BBC Bitesize
Wikipedia
Wikimedia Commons
Image Source:
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Commons
Flickr
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