AP Biology

Why do Venus flytraps have flytraps?

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Plant Nutrition(Ch 38)

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Physiological adaptation

Dogs pee on trees…Why don’t trees pee on dogs?

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Physiological adaptation

Dogs pee on trees…Why don’t trees pee on dogs?

NH3NH3

animal wasteanimal waste

plant nutrientplant nutrient

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Nutritional needs Autotrophic does not

mean autonomous plants need…

sun as an energy source inorganic compounds

as raw materialswater (H2O)

CO2

minerals

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Macronutrients Plants require these nutrients in

relatively large amounts C, O, H, N, P, K, Ca, Mg, S

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Mineral absorption Proton pumps

active transport of H+ ions out of cell chemiosmosis H+ gradient

creates membranepotential difference in charge drives cation uptake

creates gradient cotransport of other

solutes against theirgradient

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Micronutrients Plants require in very small amounts

Cl, Fe, Mn, Bo, Zi, Ni, Mb primarily cofactors for enzyme function

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Nutrient deficiencies Lack of essential nutrients

exhibit specific symptoms dependent on

function of nutrient dependent on

solubility of nutrient

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Magnesium deficiency Symptoms

chlorosis = yellowing of leaves Why? What is magnesium’s function?

Take 2 fertilizer pellets

& call me in the morning

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Chlorophyll

Why does magnesium deficiency cause chlorosis?

The chlorosis shows up in older leaves first, because plant moves Mg+ to newer leaves. Why?

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The role of soils Plants are dependent on soil quality

texture / structure relative amounts of various sizes of soil particles

composition organic & inorganic chemical components fertility

Agronomistsreally dig dirt!

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Importance of organic matter Topsoil

most important to plant growth rich in organic matter

humus decomposing organic material

breakdown of dead organisms, feces, fallen leaves & other organic refuse by bacteria & fungi

improves soil texture reservoir of minerals

organisms 1 tsp. of topsoil has ~5 billion bacteria

living with fungi, algae, protists, insects, earthworms, nematodes

So don’t rakeyour lawn or

bag your leaves

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Soil health as a global issueNot taking care of soil health has far-reaching, damaging consequences

1920’s Dust Bowl lack of soil conservation

growing the same crop year after year (wheat)

grazing by cattle bare ground exposed to

wind erosion in winter drought

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Soil health as a global issue Soil conservation & sustainable agriculture

maintaining healthy environment sustainable production of food supply economically viable farming industry

contour plowing crop rotation

“A sustainable agriculture does not deplete soils or people.” – Wendell Berry

cover crops

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Global issues soil fertility erosion irrigation forestry destruction

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Fertilizers “Organic” fertilizers

manure, compost, fishmeal

“Chemical” fertilizers commercially manufactured N-P-K (ex. 15-10-5)

15% nitrogen 10% phosphorus 5% potassium

What are thepolitical, economic,

environmentalissues?

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Nitrogen uptake Nitrates

plants can only take up nitrate (NO3-)

Nitrogen cycle by bacteria trace path of nitrogen fixation!

What will the plant use N for?

root

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Soybean root nodules N fixation by Rhizobium bacteria

symbiotic relationship with bean family (legumes)

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Increasing soil fertility Cover crops

growing a field of plants just to plow them under usually a legume crop taking care of soil’s health

puts nitrogen back in soil

erosion control, too

Plow it under?Why would you

that?

AP Biology 2006-2007

Some plant oddities…

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Parasitic plants tap into host plant vascular system What are the pros and cons? Indian pipe

Mistletoe

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Carnivorous plants

Why do they do this? In what type of

environment would they be found?

Pitcher plantVenus fly trapSundew

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Pitcher plants

Sundews

Venus flytrap

Figure 37.15c

AP Biology Pitcher plant

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Plants of peat bogs High acid environment

most minerals & nutrients bound up & are not available to plants must find alternative sources of nutrients

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Mycorrhizae increase absorption Symbiotic relationship between fungi & plant

symbiotic fungi greatly increases surface area for absorption of water & minerals

increases volume of soil reached by plant increases transport to host plant

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REVIEW1. How is symbiosis critical to plant

survival and evolution?

2. How do plants take in nutrients?

3. Name two critical nutrients, and state what outcome their deprivation would have on plants.

AP Biology 2006-2007

Any Questions??