Stuff Im shaky on Flashcards
1
Q
What is cell differentiation?
A
Differentiation is the process by which a cell changes to become specialised for its job
2
Q
Compare plants and animal cell differentiation capabilities?
A
- In most animal cells, the ability to differentiate is lost at an early stage, after they become specialised
- Lots of plant cells never lose the ability to differentiate
3
Q
How are sperm cells differentiated for reproduction?
A
- Sperm cells contain the genetic information from the male parent. They have to break the females egg
- The middle section is filled with mitochondria, transferring the energy needed for the tail to work
- Long tail and streamlined head to help it swim to the egg
- The acrosome contains digestive enzymes for breaking down the outer layers of the egg
4
Q
How are nerve ceclls differentiated for rapid signalling?
A
- Lots of dendrites to make connections to other nerve cells
- Nerve endings or synapses adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals
5
Q
How are muscle cells specialised for contraction?
A
- Contain lots of mitochondria to transfer the energy needed for contraction
- They contain special proteins that slide over each other making the fibres contract
- They can store glycogen to transfer the energy needed for the fibres to contract
6
Q
How are root hair cells specialised for absorbing water and minerals?
A
- They greatly increase the surface area available for water to move into the cell
- They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell
- They have many mitochondria to transfer the energy needed for active transport
7
Q
How are xylem cells specialised for carrying water and mineral ions?
A
- The spirals and rings of lignin in the xylem cells make them very strong and help the withstand the pressure of water moving up the plant
- The cells in xylem are dead and form long hollow tubes that allow water and mineral ions to pass easily through them from one end of the plant to the other
8
Q
How are phloem specialised to carry food?
A
- The sieve plates allow water carrying dissolved food to move freely up and down the tubes to where it is needed
- The mitochondria of the companion cells transfer the energy needed to move dissolved food up and down the plant in phloem
9
Q
How are alveoli specialised to maximise diffusion?
A
- Massive surface area
- Moist lining to dissolve gases
- Very thin walls
- Good blood supply
10
Q
Purpose of villi?
A
- The inside of the small intestine is covered in millions and millions of tiny projections called villi
- They increase the surface area in a big way so that digested food is absorbed much more quickly into the blood
- They have a single layer of surface cells
- They have a very good blood supply to assist quick absorption
11
Q
How are leaves adapted for gas exchange?
A
- The underneath of a leaf is an exchange surface. It is covered in stomata which carbon dioxide diffuses through
- The size of the stomata are controlled by guard cells. These close the stomata if the plant is losing water faster than it is being replaced by the roots. Without guard cells a plant would wilt
- The flattened shape of the leaf increases the areas of this exchange surface so that its more effective
12
Q
How are gills adapted for gas exchange?
A
- Each gill is made of thin plates called gill filaments which give a big surfacae area for exchange in gases
- The gill filaments are covered in lamellae, which incresae the surface area even more
- The lamellae have loots of blood capillaries to speed up diffusion
- Thin surface layer of cells to minimise the distance that gases have to diffuse
- Blood flows through the lamellae in one direction and water flows over in the opposite direction. This maintains a large concentration gradient between the water and the blood
13
Q
What are chromosomes?
A
- The nucleus contains your genetic material in the form of chromosomes
- Chromosomes are coiled up lengths of DNA molecules
14
Q
How many chromosomes are in the nucleus?
A
46
15
Q
How many chromosomes are in the nucelus of gametes?
A
23
16
Q
What does the cell cycle do?
A
The cell cycle makes new cells for growth, development and repair
17
Q
What is stage 1 of the cell cycle?
A
- Stage 1 is called interphase
- This is the longest stage in the cell cycle
- The cells replicate their DNA to to form two copies of each chromosome - one for each new cell
- They increase the number of sub-cellular structures such as mitochondria and ribosomes ready for division
18
Q
What is stage 2 of the cell cycle?
A
- Stage 2 is called mitosis
- The chromosomes line up at the center of the cell and cell fibres pull them apart. The two arms of each chromosome go to opposite ends of the cell
- Membranes form around each of the sets of chromosome - these become the nuclei of the two new cells
19
Q
What is stage 3 of the cell cycle?
A
- Stage 3 is called cytokinesis
- The cytoplasm and cell membrane divide
- This forms two identical daughter cells
20
Q
What is binary fission?
A
Binary fission is how prokaryotic cells replicate
21
Q
Process of binary fission?
A
- The circular DNA and plasmids replicate
- The cell gets bigger and the circular DNA strands move to opposite poles of the cell
- The cytoplasm begins to divide and new cell walls begin to form
- The cytoplasm divides and two daughter cells are produced
- Each daughter cell has one copy of the circuar DNA but can have a variable number of copies of the plasmids
22
Q
How to culture bacteria in the lab?
A
- Sterilise the inoculating loop used to transfer microorganisms to the agar by heating it in the flame of a bunsen until it is red hot and then letting it cool
- Dip the sterilised loop in the suspension of the bacteria you want to grow and use it to make zigzag streaks across the surface of the agar. Replace the lid on the petri dish as quickly as possible to prevent contamination
- Fix the lid of the petri dish with adhesive tape to prevent microorganisms from the air from contaminating the culture, or microbes from the culture escaping
- The petri dish should be stored upside down to prevent drops of condensation falling onto the agar surface
23
Q
What are stem cells?
A
- Stem cells are undifferentiated cells
24
Q
What are embryonic stem cells?
A
- Stem cells that can differentiate into any kind of cell
- They come from early human embryos
25
What are adult stem cells?
1. Stem cells in adults that are only found in certain places like bone marrow
2. They can't turn into any type of cell, only certain ones, like blood cells
26
How are stem cells used to cure diseases?
1. Medicine already uses adult stem cells to cure disease. E.g., stem cells are transferred from the bone marrow of a healthy person can replace faulty blood cells
2. Embryonic stem cells can be used to replace faulty cells in sick people - you could make insulin-producing cells for people with diabeties, nerve cells for people paralysied by spinal injuries
27
What is therapeutic cloning?
1. An embryo can be made from the same genetic information as the patient
2. This means that the stem cells produced from it would also contain the same genes and so wouldnt be rejected by the patients body if used to replace faulty cells
28
Cons of stem cell research?
1. They believe human embryos shouldnt be used for experiments since they are potential human life
2. Stem cells from another person might be rejected by the patient’s immune system
29
Where are undifferentiated cells found in plants?
Meristems
30
How can stem cells in plants be used to clone them?
1. In plants, stem cells are found in the meristems
2. Throughout the plants entire life, cells in the meristematic tissue can differentiate into any type of cell
3. These stem cells can be used to produce clones of whole plants quickly and cheaply
4. They can be used to grow more plants of rare species
5. They are also used to grow crops of identical plants that have desired features for farmers
