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What factors affect plant growth? LO- to explain the factors which affect plant growth Green plants absorb light energy using chlorophyll in their leaves. They use it to react carbon dioxide with water to make a sugar called glucose. The glucose is used in respiration, or converted into starch and stored. Oxygen is produced as a by-product.
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What factors affect plant growth?
LO- to explain the factors which affect plant growth What factors
affect plant growth?
LO- to explain the factors which affect plant growth Green plants
absorb light energy using chlorophyll in their leaves. They use it
to react carbon dioxide with water to make a sugar called glucose.
The glucose is used in respiration, or converted into starch and
stored. Oxygen is produced as a by-product. During
photosynthesis:
Light energy is absorbed by chlorophyll, a green substance found in
chloroplasts in some plant cells and algae Absorbed light energy is
used to convert carbon dioxide (from the air) and water (from the
soil) into a sugar called glucose Oxygen is released as a
by-product This equation summarises what happens in photosynthesis:
Some glucose is used for respiration, while some is converted into
insoluble starch for storage. The stored starch can later be turned
back into glucose and used in respiration. Without enough light, a
plant cannot photosynthesise very quickly, even if there is plenty
of water and carbon dioxide. Increasing the light intensity will
boost the speed of photosynthesis. Sometimes photosynthesis is
limited by the concentration of carbon dioxide in the air. Even if
there is plenty of light, a plant cannot photosynthesise if there
is insufficient carbon dioxide If it gets too cold, the rate of
photosynthesis will decrease. Plants cannot photosynthesise if it
gets too hot. If you plot the rate of photosynthesis against the
levels of these three limiting factors, you get graphs like the
ones above. In practice, any one of these factors could limit the
rate of photosynthesis. Storage & Use Of Glucose
The glucose produced in photosynthesis may be used in various ways
by plants and algae. Storage Glucose is needed by cells for
respiration. However, it is not produced at night when it is too
dark for photosynthesis to happen. Plants and algae store glucose
as insoluble products. These include: Starch Fats and oils Use Some
glucose is used for respiration to release energy. Some is used to
produce: Cellulose - which strengthens the cell wall Proteins -
such as enzymes and chlorophyll Plant nutrients Plants need
nutrients to stay healthy and grow. The most common type of
fertilisers used contain NPK N- nitrogen P- phosphorous K-
potassium fertilisers contain minerals such as:
nitrates which are needed to makeproteins. Proteins are needed for
cell growth phosphates for respiration and growth potassium
compounds for respiration and Photosynthesis magnesium compounds
for photosynthesis. mineral deficiencies to the resulting poor
plant growth:
nitrate poor growth and yellow leaves phosphate poor root growth
and discoloured leaves potassium poor flower and fruit growth and
discoloured leaves magnesium yellow leaves. Nitrogen is needed for
plant growth as it is used to make proteins, too little nitrogen
and the plant will have stunned growth, too much then the plant
will grow too quickly, become long and spindly and then will be
prone to wind damage. Phosphate is needed for respiration and
growth of the plant, without it plants will have yellow leaves and
the roots will grow slowly Potassium is needed for respiration and
photosynthesis ( its is used to make the enzymes used in these
processes), without it the leaves will turn yellow/brown at the
edges and the plant will have less flowers and fruit Magnesium
makes the compounds needed for photosynthesis, without it the plant
will have yellow leaves and less crops will be produced Nutrients
get into the plant through the roots, they dissolve in water to
make soil solution, the nutrients travel through the plant in the
xylem Fertilisers-substance added to the soil to improve plant
growth
Organic fertiliser- a natural substance such as manure, bone meal
and wood ash Inorganic fertiliser-chemicals made with the right
balance of each nutrient Organic fertilisers Inorganic fertilisers
Signs of a unhealthy plant.
Wilting- the cells are flaccid Slug snails and fungi on the plants
Explain why plant nutrients are important and the problems the
plant may have if they do not have enough nutrients What factors
affect plant growth?
LO- to explain the factors which affect plant growth Economics Of
Greenhouse
Farmers can use their knowledge of factors limiting the rate of
photosynthesis to increase crop yields. This is particularly true
in greenhouses, where the conditions are more easily controlled
than in the open air outside: The use of artificial light allows
photosynthesis to continue beyond daylight hours. Bright lights
also provide a higher-than-normal light intensity. The use of
artificial heating allows photosynthesis to continue at an
increased rate. The use of additional carbon dioxide released into
the atmosphere inside the greenhouse also allows photosynthesis to
continue at an increased rate. Paraffin lamps have traditionally
been used in greenhouses. Their use increases the rate of
photosynthesis because as well as the light generated from the
lamps, the burning paraffin produces heat and carbon dioxide too.
Pollination is the transfer of pollen from the anther to the sigma,
this is needed for fertilisation. There are two main ways for
pollen to be transferred; by insects and by the wind Insect or wind
pollination? Cross pollination is the transfer of pollen from one
plant to another
Cross pollination is the transfer of pollen from one plant to
another. This is done to increase the gene pool. To stop self-
pollination some plants are dioecious which means that male and
female parts are on different flowers. Anthers and stigma may
mature at different times on some plants. A seed contains
everything a plant needs to grow
A seed contains everything a plant needs to grow. It contains
enough food for the plant till it gets to a stage where the plant
can photosynthesise The testa protects the seed from attacks by
insects
The micropyle is a small hole inside thetesta which allows water
into the seed, this will cause is to swell and split the testa-
ready for germination The cotyledons form the first two leaves of
the plant The pulmule forms the roots when a plant germinates, and
the radicle forms the shoots To germinate, plants need water,
oxygen and the correct temperature
To germinate, plants need water, oxygen and the correct
temperature. oxygen is needed for respiration to provide the energy
needed for growth Seeds are said to be dormant before they
germinate Breeding Plants Look at this list of characteristics of
strawberry plants. Plants will not die in temperatures below 4C
Strawberries rot quickly strawberries stay fresh for a week after
picking Big strawberries Plants produce lots of strawberries Plants
are resistant to disease strawberries are bright red strawberries
are very tasty strawberries are juicy Small strawberries Plants can
survive with little water. Plants have small leaves Which
characteristics are important to:a) A farmer, b) A shopper? If you
were a plant breeder, which 5 characteristics would you like your
new variety of strawberries to have?Explain your choices. What is
selective breeding and genetically modified food?
LO- to explain the advantages and disadvantages of selective
breeding and GM food Selective breeding is the process where plants
or animals are breed for a chosen characteristicthey can be
selectively bred to improve yield, resistance to disease and
climate, taste and appearance When two different species are
crossed a hybrid is produced
Hybrid vigour is when characteristic in the offspring have improved
from the characteristic in from the parents Genetic engineering
allows use to put a gene from one organism into another organism to
give it new characteristics For example a gene from a fish which
can live in cold seas can be put into tomato plants to allow it to
survive in cold climates. GE could also be used to kill weeds
People worry as they we do not know the consequences of eating
genetically modified food and we do not know what it will do to the
environment Will these genes be transferred to weeds? What will
happen to the biodiversity? Task- create a farm which is pro
selective breeding and genetically modified food:
what characteristics have the plant been selected for? What are the
advantages and disadvantages of selectively breeding of plants? How
could you use selective breeding to increase crop yields? How could
you improve crop by genetic engineering? Inside the nucleus of a
cell we find our DNA
Inside the nucleus of a cell we find our DNA. A gene is a section
of DNA which codes for a trait (eg hair colour, eye colour). Genes
are grouped together in chromosomes. The genetic make up of an
organism is called its genotypes. Thereare two genes for each
characteristic/trait. The organisms phenotype is the
characteristics/trait we see. Different copies of the same gene are
called alleles
Different copies of the same gene are called alleles. Alleles may
be dominant or recessive. Dominant alleles are always expressed
over recessive alleles. Monohybrid inheritance
When the F1 generation was crossed with F1 generation (e. g
When the F1 generation was crossed with F1 generation (e.g. round
seed(F1) & round seed(F1) crossed), both round and wrinkled
seeds were produced. This tell us about that traits are determined
by two different allelles, one dominant and one recessive. We
cultivate soil to make it ready to grow crops
We cultivate soil to make it ready to grow crops. We remove weeds
and improve the soil structure. In autumn we fork the soil to
loosen it up. This allows air in and allows the soil to break down
due to frost. We out trenches into clay soil to increase the
surface area which allows weathering to break up the soil and the
soil to aerate as water can drain out more easily. Single Digging
aerates the soil removes weeds improves drainage FYM can be added
to improve crumb structure raked to produce a good tilth Soil
crumbs are formed from inorganic soil particles sand, silt and
clay, are held together by humus. A good soil crumb is important to
allow the soil to be aerated, retain moisture and nutrients and
allow the water to drain. If the soil is too dense the roots will
find it difficult to grow and the soil will become water logged, if
it is too sandy it will drain too easily washing away the nutrients
and the structure will not support the plants. We can improve the
soil fertility by adding humus, compost or well rotted manure to
the soil, they are all rich in nutrients especially nitrates. They
will release nutrients over a period of time. Clay Water Humus Sand
Silt Lime can be added to clay soil, it causes the soil to
flocculate which means it sticks together to allow the soil to
aerate and drain. It is also an alkali so can neutralise acidic
soil. Sand can be added if you need to drain clay soil very quickly
but can make it heavier. Storing Crops Ripening Bruising Diseases
Pests A problem with storing food is their perishability- the
likely hood they will spoil or decay. This is caused by the growth
of fungi, moulds and bacteria on the crop. Pest and disease are
another problem, rats and mice will invade barns which contain
stores of food. Animal pests will bring disease. Managing pests
Loweringthe temperature of stored food will stop pest beingable to
survive which will prolong the life of the food. Respiration is
reduced at lower temperatures. The atmosphere can be controlled so
there is not enough oxygen for organisms to survive Fruit is
normally picked before it is ripen and the gas ethylene is used to
ripen the fruit
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