Bio - Plants
- Created by: caitlinpm
- Created on: 14-06-17 10:04
View mindmap
- Plants
- Cells
- Structure of a plant cell
- Nucleus - controls cell's activity and contains genetic material
- Cytoplasm - where most of the chemical reactions take place
- Cell membrane - controls movement of substances in and out of the cell
- Mitochondria - where aerobic respiration takes place (the powerhouse of the cell)
- Ribosomes - creates proteins
- Cell wall - made of cellulose, strengthens the cell
- Vacuole - filled with sap which supports the cell
- Transport in and out of cells
- Osmosis
- Movement of water particles from a low to a high concentration through a partially permeable membrane
- Plants gain water by osmosis through their roots.
- Diffusion
- the movement of particles from a high to a low concentration
- Oxygen and carbon dioxide diffuse during gas exchange in plant leaves
- Active transport
- Movement of molecules across a membrane from a low to a high concentration.
- Because the molecules are moving against a concentration gradient, it requi8res energy from the cells
- Plants use active transport to absorb minerals.
- Minerals cannot be absorbed using osmosis because osmosis is for water only
- Minerals cannot be absorbed by osmosis because the minerals are in very low concentration
- Movement of molecules across a membrane from a low to a high concentration.
- Osmosis
- Structure of a plant cell
- Transport in plants
- Plant tissues
- Epidermis - covers the outer surfaces of the plant for protection
- Palisade mesophyll - main site of photosynthesis
- Spongy mesophyll - air spaces between the cells to allow gases to diffuse through the leaf
- Xylem - supports the plant and transports water and minerals through the plant
- Phloem - transports dissolved food materials through the plant
- Meristem tissue - produces new cells for growth
- Water transport
- Xylem
- Water and minerals are transported up the xylem vessels to the leaves and stems
- Xylem cells are arranged end to end but the cell walls break down to form hollow tubes
- The cell wall is strengthened by lignin
- BBC Bitesize
- Translocation/phloem
- The movement of sugars through phloem tissue is called translocation
- End walls of cells allow sugars through but support the tubes
- Cells arranged end to end into tubes
- Translocation/phloem
- Transpiration
- This helps to draw water up the xylem vessel
- Factors that affect transpiration
- Increase in temperature
- More energy is transferred to the water to allow it to evaporate
- Faster air flow
- Blows away water vapour allowing more to evaporate
- Increased light intensity
- Causesstomata to open
- Humidity
- Air contains more water vapour so concentration gradient for diffusion is lower
- Increase in temperature
- Stomata are closed during night.
- This reduces water loss as carbon dioxide is not needed for photosynthesis
- Translocation/phloem
- The movement of sugars through phloem tissue is called translocation
- End walls of cells allow sugars through but support the tubes
- Cells arranged end to end into tubes
- Root hair cell
- Lots of mitochondria for active transport of minerals
- Large surface area to absorb water and minerals
- minerals are absorbed in the soil water as mineral ions
- nitrate is for making amino acids, which are used to make proteins
- deficiency causes stunted growth
- magnesiumis for making chlorophyll
- deficiency causes yellowing leaves
- nitrate is for making amino acids, which are used to make proteins
- Xylem
- Plant tissues
- Plant diseases
- Detecting/ identifying plant disease
- signs that a plant is diseased
- stunted growth
- spots on leaves
- areas of decay
- growths
- malformed stems or leaves
- discolouration
- presence of pests
- how to identify the disease
- consulting a gardening manual or website
- taking infected plants to a lab to identify the pathogen
- using testing kits, which contain monoclonal antibodies
- signs that a plant is diseased
- Examples of plant diseases
- Tobacco Mosaic Virus (TMV)
- Infects plants such as tobacco and tomato plants
- Produces a distinctive 'mosaic' pattern of discolouration on the leaves
- reduces chlorophyll content and affect photosynthesi,which affects growth
- Rose black spot is a fungal disease
- Aphids (greenflies/blackflies) are small insects that feed from the phloem, taking sugars away from the plant
- Non-communicable diseases include a range of deficiency diseases, caused by a lack of mineral ions in the soil
- stunted growth is caused by nitrate deficiency, because nitrates are needed for protein synthesis
- chlorosis is caused by magnesium deficiency, because magnesium ions are neededmake chlorophyll
- Tobacco Mosaic Virus (TMV)
- plant defences
- physical defences
- cellulose cell walls
- tough waxy cuticle on leaves
- Layers of dead cells around stems, which fall off and take pathogens with them
- chemical defences
- antibacterial chemicals, made by plants such as mint and witch hazel
- poisons deter herbivores, made by plants such as foxglove, tobacco and deadly nightshade
- mechanical adaptions
- thorns and hair to deter animals from eating/touching them
- leaves that droop or curl when touched
- mimicry to trick animals into not eating them e.g. white dead nettle does not sting, but look very similar to stinging nettle
- physical defences
- Detecting/ identifying plant disease
- Cells
Comments
No comments have yet been made