B4 Flashcards
What is respiration?
The process of transferring energy from the breakdown of glucose
Why is ATP made?
Because the energy transferred by respiration cannot be used directly by cells so instead it is used to make ATP
What is the balanced symbol equation for aerobic respiration?
C6H12O6 + 6O2 -> 6H2O + 6H2O
What is aerobic respiration?
It occurs when there is lots of oxygen available- it breaks down glucose and combines it with oxygen to make water and CO2 (waste product)
It produces 32 molecules of ATP for every molecule of glucose (most efficient way)
Where does aerobic respiration occur in prokaryotic cells?
In the cytoplasm
Where does aerobic respiration occur in eukaryotic cells?
In the mitochondria
What is anaerobic respiration?
It occurs when there is not enough oxygen present- it partially breaks down the glucose and for animals produces lactic acid (a waste product), whereas for plants it produces ethanol and CO2.
It produces only 2 molecules of ATP for every molecule of glucose (less efficient than aerobic)
What does the cell cycle do?
It makes new cells for growth or repair
Name the two phases of the cell cycle
Interphase and Mitosis
Summarize interphase
The cell grows and increases the number of subcellular structures.
It then duplicates its DNA, so there’s one copy for each new cell.
The DNA forms X-shaped chromosomes, where each arm is a copy of the other
Summarize mitosis
Cell fibres pull apart the chromosomes, making the two arms of the chromosome go to the opposite ends of the cell.
Membranes form around each set of chromosomes- these become the nuclei for the new cells. The nucleus divides.
Lastly, the cytoplasm and cell membrane divide.
The product is two new daughter cell, genetically identical to each other and the parent cell
What are auxins?
Plant growth hormones- in shoots extra auxins accelerate growth and in roots extra auxins inhibit growth
Explain positive phototropism of shoots
When a shoot is exposed to light, it accumulates more auxins on the shaded side, making the shaded side grow faster, causing it to bend towards the light
Explain positive gravitropism of roots
A root growing sideways will have more auxins on its lower side, however, in roots auxins inhibit growth, causing the root to grow down
Explain how phototropism and gravitropism helps plants to survive
Because it means the plant will grow towards the light, meaning it will absorb more light for photosynthesis and it will grow downwards, meaning the root is more likely to find more water and minerals
What do animals and some bacteria produce during anaerobic respiration?
Lactic acid
What do plants and some microorganisms produce during anaerobic respiration?
Ethanol and carbon dioxide
What is cancer?
A case of uncontrollable cell division
What are the advantages of electron microscopes? (2 things)
You can see things at a higher magnification and resolution
What is the equation linking eyepiece lens magnification, objective lens magnification and total magnification?
Total magnification = Eyepiece lens magnification x Objective lens magnification
Question:
If the eyepiece lens magnification of a microscope is 10, and the total magnification is 400, what is the objective lens magnification?
400/10=40
Answer: 40
What is the equation linking magnification, measured size and actual size in microscopes?
Magnification = Measured size / Actual size
In animals, what are the two gametes?
Sperm and egg cells
What does each gamete contain?
23 chromosomes
What does the fusion of the male and female gamete in animals produce?
A fertilised egg, known as the zygote
Summarize division 1 of meiosis
- chromosomes line up in pairs
- pairs pulled apart
- some of the father’s chromosomes and mother’s chromosomes go into each new cell
- the chromosome number of each new cell is half that of the original cell
Summarize division 2 of meiosis
- chromosomes line up again
- pulled apart
- 4 gametes are produced that are genetically different
What are light microscopes?
Work by passing light through the specimen
-they let us see things like the nuclei and chloroplasts
What are electron microscopes?
Use electrons rather than light
- higher magnification and resolution than light microscopes
- allow us to see internal structure of things like chloroplasts
What is a feature of embryonic stem cells and what does that allow them to do?
They are unspecialised, meaning they are able to divide to produce any type of specialised cell (e.g. blood cells). All embryonic stem cells are unspecialised until the 8 cell stage
What is the process of stem cells becoming specialised called?
Differentiation
What are adult stem cells?
They are stem cells found in certain places like bone marrow, but they can only differentiate into certain types of cells
All stem cells are unspecialised (True or False)
True
What do meristems produce?
Unspecialised cells that are able to divide to form any cell type, however, unlike human stem cells, plant stem cells are able to do this for the whole of the plants life.
What are risks of stem cell use in medicine? (2 things)
- Tumour development: stem cells divide very quickly, and if this is uncontrollable, a tumour may develop
- Disease transmission: viruses live inside cells and if these go undetected, then the disease will be passed on
How can embryonic stem cells be used in medicine?
As stem cells are unspecialised, and can differentiate into any type of specialised cell, therefore it may be possible to use stem cells to replace those which have been damaged by disease or injury
What is the main ethical argument against the use of embryonic stem cells?
In order to take out embryonic stem cells, the embryo will be destroyed- this means the destruction of a potential human life
Explain negative gravitropism is shoots
A shoot growing sideways will gather more auxins on the lower side, causing it to grow faster, bending the shoot upwards
Explain negative phototropism in roots
A root being exposed to the light will gather more auxins on the shaded side, and as in roots auxins inhibit growth, the root will bend downwards away from the light and further into the soil
What is dormancy in plants?
When seeds won’t germinate (start growing)
What do gibberellins do for a plant?
- They break the dormancy of seeds and allow germination
- They trigger a response called ‘bolting’, where the plant produces lots of flowers before death in order to maximise reproduction
What does ethene do for a plant?
- It causes leaves to fall of the plant
- It stimulates the enzymes that causes fruit to ripen
