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Photosynthesis, respiration
Define photosynthesis
photosynthesis is a process in green plants which involves absorbing solar energy to manufacture carbohydrates for respiration.
Word equation for photosynthesis
water + carbon dioxide = glucose + oxygen
what’s a permanent vacuole
a sack which contains a sugary liquid. It stores water
Unbalanced and balanced equations for photosynthesis
unbalanced: CO2 + H2O → C6H12O6 + O2
balanced: 6CO2 + 6H2O → C6H12O6 + 6O2
What factors affect photosynthesis
chlorophyl quantity, light intensity, temperature, carbon dioxide supply
How does light intensity limit photosynthesis?(effects of too little and too much)
too little = plant doesn’t absorb enough light energy for chloroplasts to act/photosynthesise
too much = high supply to the point that the other factors are inadequate to keep up with the increasing amount of light energy being received so photosynthesis reaches a constant rate
How does temperature limit photosynthesis?(effects of too little and too much)
too little = plant’s enzymes have less kinetic energy so photosynthesis is either slower or ultimately stops(freezes)
too much = exceeds optimum enzyme activity point; temperature is too high so enzymes denature
(the chemical reactions involved in photosynthesis are controlled by enzymes)
How does chlorophyl quantity limit photosynthesis?(effects of too little or too much)
too little = plant can’t absorb enough solar energy to support photosynthesis
too much = other required factors are inadequate to keep up with the amount of chlorophyl so ROR doesn’t increase
How does carbon dioxide quantity limit photosynthesis?(effects of too little or too much)
too little = slow ROR because of little CO2 present to convert into sugars/glucose(photosynthesise)
too much = other factors are inadequate to keep up with the increasing amount of CO2 being received so photosynthesis reaches a constant rate (otherwise, it’d keep increasing as long as other factors are increasing asw)
How is the epidermis adapted to its function
The transparency of the epidermis enables sunlight to reach the chlorophyll-rich cells below, facilitating photosynthesis. Small openings called stomata, regulated by guard cells, allow for gas exchange, balancing CO₂ intake for photosynthesis with water conservation.
How is the palisade mesophyll adapted to its function
It contains tightly packed cells filled with numerous chloroplasts, maximizing the absorption of sunlight. These cells are elongated and arranged vertically, ensuring efficient light capture and minimal shadowing. The thin cell walls facilitate rapid gas exchange, allowing carbon dioxide to diffuse in and oxygen to diffuse out easily. The arrangement of these cells near the upper surface of the leaf ensures they receive the most light.
How is the spongy mesophyll adapted to its function
It consists of loosely packed, irregularly shaped cells, creating numerous air spaces that facilitate the movement of gases (CO2 & O2). These cells contain chloroplasts, but less than the palisade mesophyll. The large surface area of the cells enhances gas exchange and helps in maximizing light absorption. The proximity of the spongy mesophyll to the stomata ensures that gases can quickly diffuse into and out of the leaf, optimizing the process of photosynthesis and respiration.
Purpose of cuticle for leaf
The cuticle is a protective, waxy layer covering the epidermis of a leaf; its primary purposes are to minimize water loss by reducing transpiration and to protect the leaf from environmental damage. This waxy barrier helps the plant retain moisture, especially in dry conditions. Also, the cuticle serves as a protective shield against pathogens, such as bacteria and fungi, as well as harmful UV radiation.
Aerobic respiration word and chemical equation in plants and animals
both: glucose + oxygen → carbon dioxide + water + energy
Anaerobic respiration word and chemical equation in plants and animals
in plants: glucose → ethanol + carbon dioxide + energy (ATP)
in animals: glucose → lactic acid + energy (ATP)
ways in which energy released from respiration is used by an organism
cell growth and repair
protein synthesis
muscle contraction
sending nerve impulses
absorbing molecules via active transport
how do plants and animals physically take in oxygen for respiration?
plants: via tiny pores (stomata) on their leaves
animals: through ventilation system
P.S: Both respire without stopping. Plants only photosynthesise during the day, when there’s light to absorb.
What’s ATP?
a molecule that can store and transfer energy
Functions of larynx and trachea
larynx: air passage to the lungs holding vocal cords; the voice box
trachea: a stiff, flexible tube which carries air in & out of lungs. Is a reliable pathway for oxygen to enter the body. Supported by rings of cartilage that prevent it from collapsing.
pleural cavity
fluid filled space between fluid membrane which reduces friction between the lungs and chest wall during breathing
Describe inhalation processes (muscles relaxations/contractions, rib movement, air movement, chest cavity, diaphragm…)
intercostal muscles contract
ribs move up & out
diaphragm contracts & flattens
chest cavity volume increases
chest cavity pressure decreases
air moves into lungs
Describe exhalation processes (muscles relaxations/contractions, rib movement, air movement, chest cavity, diaphragm…)
intercostal muscles relax
ribs move down & in
diaphragm relaxes & moves up
chest cavity volume decreases
chest cavity pressure increases
air moves out of lungs
Which part of the body is the thoracic vertebrae?
What’s the sternum?
Explain how respiration works in alveoli
Side effects of smoking
lung disease (chronic bronchitis, ephysem)
coronary heart disease
What’s chronic bronchitis
inflammation of bronchi: tar stimulates gablet cells and mucus glands to enlarge, producing more mucus. That mucus builds up, blocking smallest bronchioles and causing infections
What’s ephysem
What occurs in coronary heart disease
Explain the percentage differences of gases in inhaled and exhaled air
inhaled air contains more oxygen than exhaled air/inhaled air contains less carbon dioxide than exhaled air
oxygen has diffused into blood in inhalation/carbon dioxide has diffused out of the blood in exhalation
carbon dioxide is produced by respiration
nitrogen is unrequired/unreleased in respiration
The carbohydrate stored in plants
Glycogen
