B1 Flashcards
What does the iodine test for? What colour does it turn if positive?
Iodine tests for starch. If positive, it turns blue-black. If negative, it should remain orange.
Give the equation for respiration.
Oxygen + glucose —> carbon dioxide + water
Give the equation for photosynthesis.
Carbon dioxide + water —> oxygen + glucose
How is the ATP produced in respiration used?
- To keep the organism warm. When an animal’s surroundings are colder than they are, they increase their rate of respiration. This transfers more energy by heating, so they can keep their body at a constant temperature.
- For movement. ATP is required to contract muscle cells that enable the organism to move.
- To synthesize larger molecules from smaller ones to make new cell material. E.g. plants make amino acids from sugars and nitrates and other nutrients, and those amino acids form proteins.
Is respiration an exothermic or endothermic reaction?
Exothermic. During the process of respiration, energy is transferred to the surroundings in the form of heat.
Where does aerobic respiration take place?
In the mitochondria.
Where does anaerobic respiration take place?
In the cytoplasm.
Give the equation for fermentation.
Glucose —> ethanol + carbon dioxide
Give the equation for anaerobic respiration.
Glucose —> lactic acid
What is anaerobic respiration in plants referred to as?
Fermentation.
State one similarity and one difference between anaerobic respiration in plants and anaerobic respiration in animals.
S - both are forms of respiration without the presence of oxygen.
D - Anaerobic respiration in plants is called fermentation, and produces ethanol and carbon dioxide instead of carbon dioxide, as it does in animals.
Why does anaerobic respiration occur?
Muscles need to transfer more energy than usual when they contract, energy that is supplied through respiration. This is why your breathing and heart rate increases during exercise to provide your cells with enough glucose and oxygen. However, during strenuous exercise, the heart rate cannot increase fast enough to meet the demand.
This is why your body starts to transfer glucose from its chemical energy store in the body through anaerobic respiration. This allows respiration to occur and energy to be transferred to the muscle cells without the presence of oxygen.
What is oxygen debt?
The oxygen needed to break down the buildup of lactic acid formed during anaerobic respiration.
Give two reasons why the body usually respires aerobically instead of anaerobically.
Aerobic respiration has a higher yield of ATP molecules per glucose molecule. This is because the glucose molecule is fully broken down.
Lactic acid formed from anaerobic respiration causes muscle cramps as it builds up in the muscle cells. This is painful and the muscles stop contracting. This is called muscle fatigue.
What is the name for the shape of DNA?
Double helix. (polymer)
What are the three components for a DNA nucleotide?
Phosphate, Deoxyribose sugar, Nitrogenous base
Use Chargaff’s rule to find out the percentage of Adenine if the percentage of Guanine is 27%.
Guanine% = Cytosine%
27% + 27% = 54%
100 - 54 = 46
46 ÷ 2 = 23
Adenine = 23%
What is the monomers of DNA called?
Nucleotides
Define a gene.
A short section of DNA that codes for a specific characteristic.
Define a chromosome.
A long molecule of DNA.
Explain why DNA is an example of a polymer.
It is a long molecule composed of many repeating monomers, called nucleotides.
Describe the structure of DNA.
It is a polymer made out of repeated monomers called nucleotides. Two strands of DNA are arranged in a double-helix shape, held together by bonds between the nitrogenous bases. These nitrogenous bases are complimentary to each other on either strand - Adenine with Thymine and Guanine with Cytosine.
What does Biuret test for? What colour does it turn if positive?
Biuret tests for protein. It should turn from blue to purple/lilac of positive.
What does is the ethanol emulsion test for? What colour does it turn if positive?
Tests for lipids. Should turn cloudy white if positive. If negative, it should remain colourless.
What does the Benedicts Test test for? What colour does it turn if positive?
Tests for reducing sugars. Should turn brick-red if positive. If negative, should remain blue.
What is produced from the breakdown of lipids?
Fatty acids and glycerol.
What are enzymes required for the breakdown of:
Lipids?
Carbohydrates?
Starch?
Proteins?
Lipids - Lipase
Carbohydrates - Carbohydrase
Starch - Amylase
Proteins - Protease
As an enzyme and substrate react, what is formed?
An enzyme-substrate complex.
Define the metabolic rate.
The rate at which chemical reactions in the cells transfer energy from its chemical stores in food.
What are two factors that could potentially denature enzymes?
Temperature
Ph
How does carbon dioxide enter plant cells?
It diffuses in through the stomata.
State stages 1 and 2 of photosynthesis.
Stage 1 (light dependent) - energy transferred from light splits water into hydrogen ions and oxygen gas.
Stage 2 (light independent) - carbon dioxide gas combines with the hydrogen ions to make glucose.
Is photosynthesis an endothermic or exothermic reaction?
Endothermic. Energy must be transferred from the surrounding for ohotosyntheiss to take place.
Define phototropism.
When a plant grows in the direction of light.
What is a photometer?
An instrument for measuring light intensity.
What is meant by the term ‘photoconductive’?
A material that decreases in resistance as it absorbs light.
Give three ways in which the plant makes use of the glucose produced in photosynthesis.
1 - Glucose not needed immediately is converted into starch to provide a store of energy for when the plant is unable to photosynthesise at night.
2 - Glucose can be converted into other sugar molecules such as fructose and sucrose.
3 - Some is used immediately in respiration.
What do stomata allow to diffuse in and out of the plant?
Carbon dioxide in, oxygen and water vapour out.
How does a plant obtain water for photosynthesis?
Water enters the roots from the soil through the root hair cells by osmosis.
Give 3 limiting factors on photosynthesis.
Light intensity.
Carbon dioxide concentration.
Temperature.
