cells and organisation (B1,B2) Flashcards
name to examples of eukaryotes
animal and plant cells
definition of a eukaryote
eukaryotic cells contain their genetic material enclosed in a nucleus
definition of a prokaryote
in prokaryotic cells, the genetic material is not enclosed in a nucleus
which are smaller eukaryotes of prokaryotes?
prokaryotes
conversion of 1cm to m in standard form
1 x 10^-2m
conversion of 1mm to m in standard form
1 x 10^-3m
conversion of 1micrometre to m in standard form
1 x 10^-6m
conversion of 1nm to m in standard form
1 x 10^-9m
what is one order of magnitude
10x
how much greater is each order of magnitude
10x greater
job of the nucleus
to enclose the genetic material
job of the cytoplasm
the watery solution where chemical reactions take place
job of the cell membrane
controls the molecules that can enter and leave the cell
job of the mitochondria
where aerobic respiration takes place
ribosomes
the sites of protein synthesis
job of the chloroplast
contains chlorophyll and are the sites of photosynthesis
job of the cell wall
made from cellulose which strengthens the cell
job of the permanent vacuole
contains fluid called cell sap which gives the plant its shape
what is differentiation
when cells become specialised
job of the sperm cell
to join with an ovum
name four adaptations of a sperm cell
enzymes - digest through ovum
nucleus - contains half the genetic information
mitochondria - provides energy for swimming
tail - can swim to the ovum, streamlined to make it easier
job of the nerve cell
to send nerve impulses around the body
name four adaptations of the nerve cell
dendrites - increase the surface area for the nerve cell
myelin - speeds up transmission of nerve impulses
axon - carries impulse from one side of the body to another
synapses - junction for the impulses to pass from one nerve cell to another
job of the muscle cells
contains protein fibres to contract and change their length
name an adaptation for muscle cells
mitochondria - provides energy for muscle contraction
point of a long root hair on a root hair cell
increases the surface area of the root
why don’t root hair cells contain chloroplasts
because they are underground
job of the xylem cell
carries water and dissolved minerals from the roots to the leaves
name two adaptations of the xylem cell
remains of end walls - form long tubes for easy flow
thick walls containing lignin - provides support to the plant causing xylem cell to die
why do xylem cells have no internal structure
so easier for water and minerals to flow
job of the phloem cells
carries dissolved sugars up and down the plant
what are companion cells
connected to phloem cells by pores, contains mitochondria to provide energy to the phloem vessel cells
properties of a light microscope
- limited magnification
- limited resolution
- coloured images
- can’t be used on living things
properties of an electron microscope
- greater magnification
- greater resolution
- image is not in colour
- specimen has to be dead
what is binary fission
when bacteria multiply by single cell division
how many pairs of chromosomes do humans have
23 pairs
process of mitosis
- DNA replicates to form two copies of each chromosome
- cell grows and copies its internal structures
- one set of chromosomes is pulled to each end of the cell
- the nucleus also divides
- the cytoplasm and cell membrane divide to form two identical cells
functions of mitosis
essential for growth of multicellular organisms
takes place when an organism repairs itself
happens during asexual reproduction
what is fertilisation
when a sperm cells joins with an ovum
What is a stem cell?
A stem cell is an undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells.
Stem cells in bone marrow differentiate to form cells in our blood.
What is the process involved in bone marrow transplants for leukemia?
- Existing bone in the patient is destroyed by radiation.
- Patient receives a transplant of bone marrow.
- Bone marrow stem cells divide to form new bone marrow and differentiate.
Leukemia is a cancer in bone marrow.
What compatibility issues can arise with bone marrow transplants?
The donor has to be compatible with the patient; otherwise, white blood cells will attack the body.
There is also a risk that viruses can be transferred.
What is therapeutic cloning?
An embryo produced with the same genes as the patient, allowing stem cells from the embryo to be transplanted into the patient without rejection by the immune system.
Stem cells can then differentiate to replace non-working cells, useful for people with diabetes or paralysis.
What are some ethical or religious objections associated with therapeutic cloning?
Concerns about the moral implications of creating embryos for research and potential life issues.
These objections vary widely among different cultures and belief systems.
Where are plant stem cells found?
In roots and buds, which contain meristem tissue.
Meristem tissue can differentiate into any plant tissue at any point.
What is one benefit of using plant stem cells?
They can clone plants quickly and cheaply to prevent extinction of certain species.
This is particularly useful for farmers.
Fill in the blank: A stem cell can differentiate into any type of _______.
[cell type]
What is diffusion?
Diffusion is the spreading out of particles resulting in a net movement from an area of high concentration to a low concentration.
How is oxygen transported into cells?
Oxygen molecules move into the cell by diffusion from an area of higher concentration to a lower concentration.
What is carbon dioxide in relation to respiration?
Carbon dioxide is a waste product of respiration within the cell.
Where does carbon dioxide move during diffusion?
Carbon dioxide moves out of the cell by diffusion from an area of higher concentration inside to a lower concentration outside the cell.
What is urea and how does it diffuse?
Urea is a waste product made by cells that diffuses out of the cells into the blood plasma and is excreted by the kidneys.
What is the first factor affecting diffusion?
Difference in concentrations.
How does the concentration gradient affect diffusion?
The greater the concentration gradient, the faster diffusion takes place.
What is the second factor affecting diffusion?
Temperature.
How does temperature affect the rate of diffusion?
The higher the temperature, the greater the rate of diffusion because particles have more kinetic energy and move faster.
What is the third factor affecting diffusion?
Surface area of the membrane.
How does surface area affect diffusion?
The greater the surface area, the greater the rate of diffusion.
What is the surface area to volume ratio for a cube with a side length of 1mm?
SA : V = 6:1.
What happens to surface area to volume ratio as organisms get larger?
The surface area to volume ratio falls sharply.
What problem does the decreasing surface area to volume ratio create for multicellular organisms?
Their surface area is not large enough for their volume, making it difficult for cells in the center to get enough oxygen by diffusion.
What structures do animals have for gas exchange?
Animals have structures for gas exchange with a high surface area, such as lungs.
What is the function of the transport system in animals?
To carry gases around the body.
How do fish obtain oxygen?
Oxygen-rich water passes into the mouth, flows over the gills where oxygen is transported into the bloodstream.
Why do gills have a large surface area?
To provide efficient diffusion pathways and maintain a high concentration gradient.
What role does an efficient blood supply play in diffusion?
It ensures that the concentration gradient is always high.
What is osmosis?
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
This process is crucial for maintaining cell turgor and overall cell function.
What happens to a cell in water during osmosis?
The cell will expand and may even burst.
This is due to the higher concentration of solutes inside the cell compared to the water outside.
What happens to a cell in a concentrated solution during osmosis?
The water will move out of the cell, causing the cell to shrink.
This process can lead to cell dehydration and loss of function.
What is the effect of osmosis on plant cells placed in water?
The cell will expand and become turgid due to the cell wall preventing bursting.
Turgidity is essential for maintaining plant structure.
What occurs to plant cells in a concentrated solution?
The cell will shrink and become flaccid due to osmosis.
Flaccidity can affect the plant’s ability to stand upright.
Define active transport.
Active transport moves substances from a more dilute solution to a more concentrated solution against the concentration gradient.
This process requires energy from respiration.
What is an example of active transport in the human body?
Sugars from the lumen of the small intestine are transported into the cell by active transport.
This allows sugars to be absorbed into the bloodstream.
How does active transport function in plants?
Active transport moves ions from the soil into the root hair cells, which are then transported into the xylem vessels.
This process is vital for nutrient uptake and distribution within the plant.
