module 4: multicellularity Flashcards
how does changes in DNA and proteins arise
through mutation
as time increases the mutation rate
also increases
what can a molecular clock do
estimate the time of divergence
what can a molecular clock do
estimate the time of divergence
how many times has multicellularity occurred
6 times
what is the process of multicellularity
-cells form a cluster
-they begin to communicate
- specialisation
- cells form tissues and organs
what are the consequences of multicellularity
- cells can perform a specific task
-cells work in unison
multicellularity enables the following
-specialisation
- formation of organs and tissues
- structurally complex bodies
-increased size
-increased efficiency
what embryogenesis
the multiple rounds of cell division when an organism is developed from a zygote
what is morphogenesis
cells and tissues arranging themselves to create the final form of the body
for animals are they organs formed when they are born
ues all of their tissues and organs are formed
for plants are their organs formed when they are born
very few organs and tissues are formed
what are ligands
a chemical signal that activates receports on nearly cells
how do plants expand if they are semi rigid
-take up water to expand vacuoles
-increased turgidity triggers the release of enzyme to soften the wall
what is expansion
a protein that looses the cell wall to allow water into the cell
how does expansin work
They disrupt the bonds between cellulose microfibrils and other cell wall components, making the wall more flexible
what is the primary cell wall
-simi rigid
-allows for expansion
what is the secondary cell wall
-thick and regid
-expansion is not possible
what are the directions of plant growth
-tropism
-phototropism
-heilotropism
what is tropism
Tropism is growth towards or away from a stimulus- light, gravity, water and touch
what is phototropism
differential growth in response to light
what is Heliotropism
growth that follows the path of the sun
what is auxin
plant growth hormone that promotes the expansion of the cell
what does auxin do
plant growth hormone that works to expand the cell by lowering the pH in the cell to activate expansion and promoting the activity of a protein pump
draw the following
draw it bitch
what does embryogenesis establish
the basic plan of the plant (the morphology of the plant)
what are the stages of plant embryogenesis
- zygote formation
- two cell stage
- octant stage
- heart stage
- mutation stage
what happens during zygote formation
Fertilization occurs when a sperm cell fuses with an egg cell, resulting in the formation of a zygote. The zygote contains the genetic material from both parents and marks the beginning of embryogenesis.
what happens during the two cell stage
At the 2-cell stage of plant embryogenesis, the zygote divides into two cells through mitosis. One cell develops into the suspensor, aiding nutrient transfer, while the other cell forms the majority of the embryo, including the shoot and root systems.
what happens at the octant stage
At the octant stage of plant embryogenesis, the embryo consists of eight cells in two tiers. The upper tier forms the proembryo, giving rise to the shoot system, while the lower tier contributes to the suspensor, supporting the embryo and aiding in nutrient transfe
what happens at the heart stage
differentiation due to different gene expression expressing particular genes within the cells
do plants grow after embryonic development
yes they grow new organs like leaves and flowers
what are stem cells
Stem cells are undifferentiated cells that can differentiate into specialized cell types and self-renew through division
what do tree rings look like in winter, summer and spring
winter- nothing
summer- dark ring
spring- light ring
reduction is turgor pressure leads to
plants become flaccid
- wilting occurs
increase in turgor pressure leads to plants being
turgid plants
how does water move up a plant
water moves up a plant through adhesion and cohesion
what is adhesion
interaction between water molecules and the xylem wall (capillary action)
-adhesion increases as the tubes diameter becomes smaller
what is cohesion
interaction of water molecules with other water molecules via hydrogen bonds
how does cohesion work
Cohesion is the intermolecular force that holds water molecules together through hydrogen bonding. It creates properties like high surface tension and allows water to climb in narrow tubes through capillary action.
what does the xylem transport
water!!!!!
what does the phloem transport
carbohydrates and other solutes
the transportation of water through the xylem is call
transpiration
the transportation of carbohydrates and solutes in the phloem is called
translocation
if there is light the stomata will
open because
-protons are pumped out
ions enter lowering solute
-h2o enters
pores open
if there is no light the stomata will
close
- proton pump becomes less active
-ions diffuse out
-water flows by osmosis
-pressure goes down
-pores close
what is the role of companion cells
Companion cells support the function of sieve tube elements in the phloem, facilitating the transport of sugars and other nutrients in plants. They load sugars into sieve tubes, maintain energy supply, and regulate solute concentrations for efficient long-distance nutrient transport.
what is the role of sieve tubes
Sieve tubes are responsible for the long-distance transport of sugars and other nutrients in plants through the phloem.
what if the difference between sieve tubes and companion cells
-Companion cells support sieve tubes in the phloem. Companion cells provide energy, nutrient loading, and regulation of solute concentrations.
-Sieve tubes are non-living cells responsible for long-distance transport of sugars and nutrients in the plant.
what is the mass flow hypothesis
-The mass flow hypothesis explains the movement of sugars in plants’ phloem.
-Sugars are actively loaded into the phloem at source regions, creating a high concentration gradient.
-This gradient causes water to enter the phloem via osmosis, creating high turgor pressure.
-The pressure gradient drives the flow of sugars and water from source to sink regions.
-Sugars are actively unloaded at sink regions, reducing turgor pressure and allowing water to exit the phloem.
-This hypothesis suggests that the bulk flow of sugars driven by pressure differences enables long-distance nutrient transport in plants.
what is homeostasis
maintenance of a relatively stable internal environment despite changes in internal and external conditions
what is negative feedback
a feedback loop where the stimulus moves away from equilibrium by opposing the change
what is needed for cell communication
- a receptor
- a control centre
-effector
what are the 3 ways cell communicate
- cytoplasmic connection
- hormones
- lacl signalling
what do hydrophilic hormones bind to
Binds to cell surface membrane receptors
what do lipophilic hormones bind to
Binds to hydrophillic transport proteins
what does the liver store glucose as
glycogen
insulin binding activates the receptor which has 2 effects
- increase number of glucose transporters in the membreane
- activate an enzyme glycogen synthase to convert glucose into glycogen
what is glucagon
a hormone that your pancreas makes to help regulate your blood glucose
when glucose is high
high levels of glucose is detected by pancrease cells and release insulin
liver converts glucose into glycogen
blood sugar levels drops
what happens when glucose is low
pancreas cells stimulate the release of glucagon into the blood
liver breaks down glycogen into glucose and release it into the blood
glucose levels rise and glucagon is released is diminished
what happens if we drink too much water
kidneys cannot cope and organs begin to swell
isotonic meaning
equal solute concentration
hypotonic meaning
solutions surrounding the cell have lower solute concentration
hypertonic meaning
solution surrounding cell has higher solute concentration then cell
what are the 3 environments fort animals to live in
-terrestial
-fresh water
-salt water
what is an osmoconformer
osmotic concentration of internal environments is the same as the external environment
what is an osmoregulator
osmotic concentration of internal environment is different to the external environment
disadvantages of osmoconformer
· Osmoconformers usually cannot cope with large changes in the body salinity, therefore must live in environments where salinity changes little
advantages of osmoregulators
· Osmoregulator can cope with a wide range of salinities
disadvantages of osmoregulars
require a lot of energy due to their high metabolic rate
problems organisms face with salt water
-not enough water and too much salt
-not enough water and too much salt
what is the solution for salt water fish to get water
produce small amount of concentrated urine, actively excrete ions (across the gills in fish or kidneys or salt glands)
why are salmon cool
because they can live in fresh water and salt water
what do salmon do when they are in fresh water (low solute concentration)
- Don’t drink water
- Kidneys produce lots of dilute urine
Gill epithelial cells: pump Na+ and Cl- from water flowing over gills into blood to increase solute concentration of blood and body fluids
- Kidneys produce lots of dilute urine
what do salmon do in saltwater (high solute concentration)
- Kidneys produce a small amount of concentrated urine
Gill epithelial cells: pump Na+ and Cl- from blood into water flowing over gills to decreases solute concentration of blood and body fluids
what is the problem with terrestrial osmoregulator
not enough water in the environment (especially in deserts)
what is the solution that osmoregulators adapted
-get water from food and drink
-Some absorb water through skin and anus
-Minimise water loss during excretion of waste ie concentrated urine
what is a nephron
small functional unit if the kidneys
what are the functions of the nephron
-filtration
- reabsorption
- secretion
- osmosis
what is filtered in the nephron
all blood plasma except blood cells and large proteins enter tubule
what is readsorbed in the nephrons
- Na+ and Cl- ions
-amino acids
-glucose - vitamins
what type of regulation does the kidney follow
-negative feedback
what are the different types of waste from nitrogeneous waste
- ammonia
- uric acid
- urea
- guanine
what are the different types of waste from nitrogeneous waste
- ammonia
- uric acid
- urea
- guanine
what do juxtamedullary nephron do
-concentrate urine
- Establish a high osmotic concentration in the inner medulla
