Plant nutrition

PLANT NUTRITION

LO:

• Define photosynthesis • State the word equation for photosynthesis • State the balanced chemical equation for

photosynthesis • Explain the importance of chlorophyll for

photosynthesis• Outline the subsequent use and storage of the

carbohydrates made in photosynthesis

• Define the term limiting factor • Identify and explain the limiting factors of

photosynthesis in different environmental conditions

• Describe the use of carbon dioxide enrichment, optimum light and optimum temperatures in glasshouses in temperate and tropical countries

• Use hydrogencarbonate indicator solution to investigate the effect of gas exchange of an aquatic plant kept in the light and in the dark

• Identify chloroplasts, cuticle, guard cells and stomata, upper and lower epidermis, palisade mesophyll, spongy mesophyll, vascular bundles, xylem and phloem in leaves of a dicotyledonous plant

• Explain how the internal structure of a leaf is adapted for photosynthesis

• Explain the effects of nitrate ion and magnesium ion deficiency on plant growth

LO: practical work

• Investigate the necessity for chlorophyll, light and carbon dioxide for photosynthesis, using appropriate controls

• Investigate and describe the effects of varying light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis, e.g. in submerged aquatic plants

VOCABULARY

• Synthesis = building up of complex molecules from simpler substances

• Energy transducers = convertors of energy, converting light energy into chemical energy

• Autotrophic = self-feeding

• Plants are autotrophic organisms – they take simple substances from their environment and use light energy to build them up into complex food compounds

• Produce their own food in the process called PHOTOSYNTHESIS

LO: Define photosynthesis

Photosynthesis

• Photos = light• Synthesis = building up

= basic process by which plants manufacture carbohydrates from raw materials using energy from light

= is the process in which light energy, trapped by chlorophyll, is used to convert carbon dioxide and water into glucose and oxygen

LO: Define photosynthesis

Requirements for photosynthesis• Sunlight = light energy, transported in photons

• Chlorophyll = green pigment contained in chloroplasts; needed to absorb the energy from photons; energy transducers – converts the light energy into chemical energy

• Carbon dioxide from the atmosphere

• Water from the soil

• Suitable temperature

LO: State the word equation for photosynthesis, State the balanced chemical

equation for photosynthesis Equations of photosynthesis

• Chlorophyll absorbs light energy and enables it to be used to drive the reactions.

• Chlorophyll transfers light energy into chemical energy in molecules, for the synthesis of carbohydrates

• The initial products of photosynthesis are sugars (such as glucose) which can be converted to large, insoluble molecules such as starch for storage within the plant

• Photosynthesis

LO: Explain how the internal structure of a leaf is adapted for photosynthesis

The Leaf

In order to photosynthesise a leaf needs:• Exchange of gases• Delivery of water• Removal of glucose• Obsorbtion of light energy

Structure of a bifacial leaf

U = WAXY CUTICULE- Reduces water loss; it is thicker on the upper surface

P = UPPER EPIDERMIS- One cell thick; is transpaarent; prevents the entry of

disease-causing microorganisms

V = PALISADE MESOPHYLL - tall thin cells with small intercellular spaces; many

chloroplasts for maximum absorption of photons

Q & R = VASCULAR BUNDLE– Xylem – deliver water and minerals– Phloem – carry away the organic products

S = SPONGY MESOPHYLL– Loosely packed cells, covered with a thin layer of

waterW = air spaces, aid the diffusion of gasses

• T = lower epidermis

• Y =

LO: Explain how the internal structure of a leaf is adapted for photosynthesis

Stomata

• Allow the entry of carbon dioxide and the exit of oxygen

• It can be closed when no carbon dioxide intake is needed

• When a plant is short in water, the guard cells become flacid, closing the stoma

• When a plant has plenty of water, the guard cells become turgid, swell up, curve away from each other, opening the stoma

• Stomata will close:– to conserve water at night-time when photosynthesis can

no longer continue– if the plant is losing too much water– in response to wounding - plants can lose a lot of water

through open wounds and some plants, e.g. tomato plants, react rapidly to damage by transmitting electrical signals throughout their leaves which trigger the stomata to close

• Stomata will open and close according to a circadian rhythm as well as in direct response to light and dark.

• How are leaves adapted for photosynthesis

The intake of carbon dioxide andwater by plants

• Water availability:– A shortage of water closes stomata which limits

carbon dioxide uptake– There is always enough water as a subtract for

photosynthesis– The water uptake happens through the roots and

water is then transported through xylem

• Carbon dioxide– From the

atmosphere through the stoma

– Carbon dioxide cycle

LO: Define the term limiting factor

• http://www.dnatube.com/video/11622/Factors-That-Affect-Photosynthesis

• http://www.dnatube.com/video/11219/Rate-of-a-Reaction-Affecting-Factors

LO: Explain the effects of nitrate ion and magnesium ion deficiency on plant growth Plants and minerals

• nitrate ions:– for protein synthesis,

• magnesium ions – for chlorophyll synthesis.

• Is absorbed from the soil as a nitrate ions (NO3-) or

ammonium ions (NO4+)

• It is required for proteosynthesis (production of proteins)

• Deficiency: causes severe symptoms, the whole plant is stunted, with weak stem and yellowing, dying leaves

LO: Explain the effects of nitrate ion and magnesium ion deficiency on

plant growth Nitrogen

LO: Explain the effects of nitrate ion and magnesium ion deficiency on plant growth

Magnesium

• Is absorbed from the soil as magnesium ions (Mg2+)

• Forms part of the chlorophyll molecule

• Deficiency causes Chlorosis = the leaves turn yellow, usually from the bottom of the plant first

Fertilisers

• Are needed to add nitrates and phosphates to the soils

• Natural fertilisers – sewage sludge, animal manure or compost

• Artificial fertilisers – NPK contains nitrogen, phosphorus and potassium

Problems with fertilisers

• Overuse of fertilisers can cause problems of eutrophication

• The fertiliser runs off into nearby streams, rivers and lakes and boosts the frowth of algae; as algae die they are decomposed by bacteria, which use all of the oxygen dissolved in water for aerobic respiration = result = not enough oxygen for fish and insect

homework

• Page 74/2, 3a