4. Biodiversity and Natural Resources (2) Flashcards
Natural resources 4.7 - 4.15
What are the unique ultrastructures of plant cells?
Cell walls, chloroplasts, amyloplasts, vacuole, tonoplast, plasmodesmata, pits, and middle lamella.
What structures do plant cells share with animal cells?
Both cells have ribosomes, cytoplasm, mitochondria, nucleus, endoplasmic reticulum, golgi body, cell membrane, vacuole, and lysosomes.
What is the function of the cell wall in plant cells?
Rigid structure that surrounds and supports plant cells made of cellulose.
Describe chloroplasts.
Flattened structure surrounded by a double membrane with thylakoid membranes stacked to form grana linked by lamellae.
Lamellae
Thin flat pieces of thylakoid membrane
What is the function of chloroplasts?
Site of photosynthesis, production of ATP and sugars.
What is an amyloplast?
Small membrane-bound organelle containing starch granules for storage of starch grains.
What is the role of vacuoles and tonoplasts in plant cells?
Vacuoles contain cell sap and keep cells turgid; tonoplast controls what enters/leaves the vacuole.
What are plasmodesmata?
Channels in the cell walls that link adjacent cells, allowing transport of substances and communication.
What are pits in plant cells?
Regions of the cell wall where the wall is thin, allowing transport of substances between cells.
What is the middle lamella?
The outermost layer of the cell that sticks adjacent plant cells together, providing stability.
What is the structure and function of starch in plants?
Excess glucose stored as starch, which is broken down when plants need more glucose for energy. Starch is insoluble in water, preventing osmotic effects.
What is a glycosidic bond?
Covalent bond between two monosaccharides.
Describe amylose.
Long unbranched chain of alpha glucose with coiled structure due to the angle of 1,4 glycosidic bonds.
What is cellulose?
Major component of cell walls in plants, consisting of long straight unbranched chains of beta-glucose joined by 1,4 glycosidic bonds.
How are cellulose microfibrils formed?
50-80 cellulose chains linked by hydrogen bonds form strong threads called microfibrils, providing structural support.
What are sclerenchyma cells?
Cells that provide support, consisting of bundles of dead cells forming long, hollow tubes, with more cellulose than other plant cells.
What are the functions of xylem tissue?
Transports dissolved mineral ions and water, provides structural support, and forms long hollow structures from dead cells.
Why do xylem tissues have lignified cell walls?
To withstand hydrostatic pressure of water and prevent collapse.
What is the transpiration stream?
The movement of water up the stem.
What is phloem tissue?
Living tissue that transports organic compounds, particularly sucrose, from sources to sinks.
What is the role of companion cells in phloem?
Support sieve elements by carrying out cell metabolism and regulation.
What is the purpose of double-blind studies in clinical trials?
Neither the patient nor the doctor knows who receives the drug or placebo, ensuring unbiased results.
What conditions are needed for bacteria to grow?
Nutrients, oxygen for aerobic respiration, and optimal temperature and pH for enzyme function.
What is sustainability?
Using resources to meet current needs without depleting them for future generations.
How are plant fibers more sustainable than oil-based plastics?
They are biodegradable and minimize environmental pollution.
Chloroplast function
site of photosynthesis, production of ATP and sugars
Amyloplast
Small membrane bound organelle containing starch granules. Storage of starch grains => convert starch into glucose when the plant requires it
vacuole function
contains the cell sap made of enzymes, water, minerals and waste products. Vacuoles keep the cells turgid, stopping plants from wilting
What is another function of vacuoles
involved in the breakdown and isolation of unwanted chemicals in the cell
What is the function of the tonoplast
membrane surrounding vacuole, controls what enters/ leaves the vacuole
Plasmodesmata
channels in the cell walls that link adjacent cells together. allows the transport of substances and communication between cells
Pits
regions of the cell wall where the wall is thin. arranged in pairs in adjacent cells. allows transport of substances between cells
Middle lamellae
outermost layer of the cell - adhesive, sticks adjacent plant cells together, giving the plant stability.
Similarities between plant and animal cells
Both cells have ribosomes, cytoplasm, mitochondria, nucleus, endoplasmic reticulum, golgi body, cell membrane, vacuole, lysosomes
Both are eukaryotic
differences between plant and animal cells
Animal cells are heterotrophic. They cannot generate their own food via photosynthesis.
Plant cells are autotrophic. they make their own food via photosynthesis.
structure and function of starch
- excess glucose stored as starch. starch is broken down when plants need more glucose for energy.
starch is insoluble in water. so doesn’t cause water to enter cells by osmosis, therefore good for storage.(no osmotic effect)
Glycosidic bond
covalent bond between two monosaccharides
long unbranched chain of alpha glucose. the angle of the 1,4 glycosidic bonds gives it a coiled stucture => compact and good for storage.
amylose
Structure of Cellulose
long straightunbranched chains of beta-glucose joined by 1,4 glycosidic bonds
50-80 cellulose chains are linked together by a a large number of hydrogen bonds to form strong threads called microfibrils
function of cellulose
major component of cell walls in plants. Microfibrils between chains also strengthen cell wall
long branched chain of alpha-glucose. mix of 1,4 glycosidic bonds and 1,6 glycosidic bonds.
1,6 glycosidic bonds form side branches allow the enzymes that break down the molecule to breakdown the glycosidic bonds easily so that glucose can be released quickly
amylopectin
formation of cellulose microfibrils
microfibrils provide structural support for cells, strengthening cell walls. Microfibrils are in net like arrangements
How can the properties of xylem vessels and sclerenchyma fibres be exploited by humans?
Tensile strength of plant fibres used to make ropes and fabrics.
i.e. hemp
How does the arrangement of cellulose microfibrils in plant cell walls contribute to the physical properties of xylem vessels and sclerenchyma fibres?
microfibrils are arranged in a net-like arrangement. The strength and arrangement of microfibrils gives plant fibres strength.
How does the secondary thickening in plant cell walls contribute to the physical properties of xylem vessels and sclerenchyma fibres?
structural plant cells produce a secondary cell wall between the normal cell wall and the cell membrane.
It is thicker and has more lignin.
This makes plant fibres stronger.
Sclerenchyma cells
Sclerenchyma fibres are not involved in transport of substances, they provide support
Similar to xylem, they consist of bundles of dead cells
They form long, hollow tubes, but they do have end walls present
Lignification of cell walls occur, but they do not have pits like xylem vessels
They have more cellulose in their walls compared to other plant cells
Functions of Xylem tissue in a plant
Vascular tissue that transports dissolved mineral ions and water around the plant
Structural support
Xylem vessels form long, hollow straw-like structures that are formed by dead cells (due to lignification of cell walls)
DEAD
Why does xylem tissue have Lignified cell walls
pits in the walls (non lignified section), smaller diameter of vessels
lignified cell walls +> withstand hydrostatic pressure of water, impermeable to water, prevent collapse
How is flow of water left undisturbed by xylem
no end plates + no protoplasm => no end plates = allows the mass flow of water as cohesive and adhesive forces are not impeded
no protoplasm = doesn’t impede transpiration stream
why does the xylem have pits in its walls + a small diameter
lateral movement of water, allows continual flow of water in the case of air bubbles
small diameter allows capillary action, prevents water column from breaking
Why don’t xylem contain any cytoplasm or organelles
organelles could slow down the flow of water
What is a specific feature of xylem tissue that other structural tissue does not have?
There are small regions in the walls that are not lignified, known as pits, which allows for lateral movement of water and minerals between xylem vessels
Phloem tissue
LIVING TISSUE
Transport organic compounds (assimilates), particularly sucrose, from sources (e.g. leaves) to sinks (e.g. roots). The transport of these compounds can occur up and down the plant
This is known as translocation
Phloem has no support function in a plant
Where is sap found in a plant
Phloem; the organic compounds dissolve in water to form sap
Other types of phloem tissue and their roles
parenchyma for storage and strengthening fibres
parenchyma for storage and strengthening fibres
Make up phloem vessels, along with sieve tube elements.
- support sieve elements by carrying out cell metabolism and regulation.
Features of companion cells
Companion cells have a dense cytoplasm with abundant organelles, vacuoles, and large nuclei. They load and upload metabolites into the cavity of sieve elements.
vascular bundles in stem
inside to out: Xylem, phloem, Sclerenchyma
Features of a phloem sieve tube tube element and why
sieve plates with sieve pores: allows for the continuous movement of the organic compounds
cellulose cell wall: strengthens wall against hydrostatic pressure that moves assimilates
Why does a phloem sieve tube element have no organelles and a thin cytoplasm
maximises space for the translocation of assimilates.
Thin cytoplasm reduces friction to facilitate the movement of the assimilates.
Why do companion cells have a large number of mitochondria
to provide atp for the active transport of assimilates into/ out of the companion cells
other features of companion cells
transport proteins in plasma membrane, plasmodesmata in cell wall, allowing the move of organic compounds into the companion cells.
assimilate
a substance the plant takes up/ accumulates
nitrate ions role in plants
used in synthesising DNA, proteins and chlorophyll
Nitrates needed for proteins in Enzymes
These molecules are essential for plant growth, as well as the production of fruit and seeds
calcium ions in plant
these form plant important cell wall components. Plants require calcium ions for proper growth
magnesium ions in pant
Important requirement for the production of chlorophyll
This provides the green colour of stems and leaves and is essential for photosynthesis
water in a plant importance
Important component required for photosynthesis
Provides a transport medium for minerals
Maintains turgidity in plant cells though pressure in cell vacuoles
Regulates temperature - to ensure that enzymes can function at their optimum rate
transpiration stream
the movement of water up the stem
Digitalis is made of what and was discovered by whom?
Foxgloves + william withering.
foxgloves r toxic to humans.
Digitalis soup -> used to figure out the most effective concentration of digitalis.
Modern methods of drug testing
Modelling potential effects of drug using computers
Testing on human tissue, then animal.
Clinical trial -> human subjects take it
3 phases of testing during clinical trials
Phase 1 - small group, healthy individuals: reaction to drug, side effects + correct dosage
Phase 2 - group of non-healthy patients that require the drug -> determine effectiveness
Phase 3 -> comparing the drug to existing drugs to see if it works better. Patients split into two groups
Placebos
-Done in phase 2
looks exactly like the drug but contains no active ingredients
patients are not told which group they are in
so scientists can determine whether the drug actually works
placebo effect
Double blind studies
neither the patient nor the doctor knows which patient is receiving the drug or the placebo (done during phase 2 or 3 of clinical trials)
Conditions needed for bacteria to grow
nutrients to grow + respire, oxygen for aerobic respiration, temperature and pH optimal for normal enzyme function
sustainability
using resources in such a way that the requirements of the current generation are met without depleting these resources for future generations
renewable vs non renewable
solar energy vs fossil fuels
sustainable practices
minimise the damage done to the environment and its resources
Plant fibres and sustainability
plant fibres more sustainable that oil based plastics+ more sustainable
broken down by microbes to minimise environmental pollution
starch and sustainability
- used in making bioplastics
bioethanol which can be used as fuel,
more sustainable than oil and oil based plastics from fossil fuels
