b4 Flashcards
what is meant by photosynthesis?
- the reaction plants use to absorb light for their source of energy.
where does photosynthesis take place?
- in the leaves of a plant
state the word equation for photosynthesis
- carbon dioxide + water = glucose + oxygen
state the balanced symbol equation for photosynthesis
6 CO2 + 6 H2O = C6 H12 O6 + 6 O2
what kind of reaction is photosynthesis?
- endothermic, as it takes in energy.
is leaf a tissue, organ or organ system?
organ
is xylem a tissue, organ or organ system?
tissue
are roots, stem and leaves a tissue, organ or organ system?
organ system
state 5 uses of glucose
- respiration - takes place in the mitochondria
- storage - excess glucose is converted into soluble starch and stored away.
- proteins - amino acids combine with nitrate ions to make protein.
- cellulose - cell walls contain cellulose, which gives it strength.
- oils or fats - glucose produced in photosynthesis which is converted to fats and oils. it is also used as storage for energy.
by which process do we get energy from?
- respiration
state three reasons why organisms need energy?
- movement
- to keep warm
- chemical reactions to build larger molecules
where does respiration take place?
- in all living cells
what kind of reaction is respiration?
- exothermic, as it releases energy
what does the chemical symbol C6 H12 O6 stand for?
glucose
what does the chemical symbol O2 stand for?
oxygen
what does the chemical symbol CO2 stand for?
carbon dioxide
what does the chemical symbol H2O stand for?
water
what is meant by aerobic respiration and how much energy is transferred?
- in aerobic respiration, glucose reacts with oxygen
- this produces carbon dioxide and water, so a lot of energy is transferred.
what is the word equation for aerobic respiration?
- glucose + oxygen = carbon dioxide + water + energy
what is meant by anaerobic respiration and how much energy is transferred?
- when there is a shortage of oxygen, muscles respire anaerobically.
- it releases much less energy than aerobic respiration
state the word equation for anaerobic respiration
glucose = lactic acid + energy
which type of respiration takes place in yeast cells? state the name and word equation.
- anaerobic respiration
- fermentation
- glucose = ethanol + carbon dioxide
what is the economic importance of fermentation?
- it is used to make alcoholic drinks, such as beer.
- additionally, in bread, the dough rises.
what happens to the heart rate when you exercise and respire more?
- it increases to pump more oxygenated blood.
what happens to the breathing rate when you exercise and respire more?
- it increases as we breathe more frequently
what happens to the breathing volume when you exercise and respire more?
- it increases as we take deeper breaths.
what is meant by oxygen debt?
- Oxygen debt is the amount of extra oxygen the body needs after exercise to deal with the accumulated lactic acid.
- During long periods of vigorous activity, the lactic acid causes the muscles to become fatigued,so the body has to remove the lactic acid from the muscles.
what is metabolism?
- the sum of all the chemical reactions in a cell or the body.
give examples of metabolic reactions that take place in the body.
- large molecules made from small ones:
- lots of small glucose molecules are joined together to form starch, glycogen and cellulose.
- lipid molecules are made from one molecule of glycerol and three fatty acids.
- glucose is combined with nitrate ions to make amino acids, which are then made into proteins. - large molecules are broken down into small ones:
- glucose is broken down in respiration, which transfers energy to power all the reactions that make molecules.
- excess protein is broken down in a reaction to produce urea, which is excreted in the urine.
why is anaerobically transferring energy from glucose not the best way?
- as lactic acid builds up in the muscles, which can get painful.
- additionally, long periods of exercise cause muscle fatigue, which is when the muscles get tired and stop contracting efficiently.
what is inverse square law?
- the inverse law links intensity and distance.
- the law is when light intensity decreases in proportion to the square of the distance.
- light intensity = 1/d2
- as distance doubles, light intensity goes down by a factor of 4.
describe the four factors that affect the rate of photosynthesis
the limiting factors at a particular time depends on the environmental conditions:
- at night, light is the limiting factor.
- in winter, temperature is the limiting factor
- if it is sunny (warm and bright) CO2 is the limiting factor.
- chlorophyll could also be a limiting factor as it causes chloroplasts to become damaged or not make enough chlorophyll.
name the four factors that affect the rate of photosynthesis
- light intensity
- carbon dioxide concentration
- temperature
- amount of chlorophyll
how does light intensity affect the rate of photosynthesis?
- not enough light slows down the rate of photosynthesis.
- as the light level increases, the rate of photosynthesis increases steadily.
how does the carbon dioxide concentration affect the rate of photosynthesis?
- less carbon dioxide slows down the rate of photosynthesis.
- as carbon dioxide increases, the rate of photosynthesis increases as well
how does temperature affect the rate of photosynthesis?
- as the temperature increases, the enzymes involved in photosynthesis work faster, so the rate increases.
- if we keep increasing the temperature, the enzymes will denature and plants cannot photosynthesise.
how does chlorophyll affect the rate of photosynthesis?
- the amount of chlorophyll in a plant can be affected by disease or environmental stress.
- this causes chloroplasts to become damaged or to not make enough chlorophyll.
