1.1 Flashcards
1
Q
Compare prokaryotic cells to eukaryotic cells.
A
- Prokaryotes do not have DNA enclosed in a nucleus.
- Prokaryotes are smaller than eukaryotes.
- Prokaryotes do not have membrane-bound organelles like mitochondria, nuclei or vacuoles.
2
Q
What is a centi?
A
1×10-2
3
Q
What is a milli?
A
1×10-3
4
Q
What is a micro?
A
1×10-6
5
Q
What is a nano?
A
1×10-9
6
Q
Component of animal cells.
A
- Cell membrane
- Cytoplasm
- Nucleus (containing genetic material)
- Mitochondria
- Ribosomes
7
Q
Additional components of plant cells.
A
- Cell wall (made of cellulose)
- Permanent vacuole filled with cell sap.
- Chloroplasts (containing chlorophyll)
8
Q
Components of bacterial cells.
A
- Cell wall (made of peptidoglycan)
- Cell membrane
- Cytoplasm
- Nucleoid (area where all/most genetic material is found)
- Plasmids
- Ribosomes
9
Q
Function of cell wall.
A
Strengthen the cell.
10
Q
Function of cell membrane.
A
Control the substances that enter and exit the cell.
11
Q
Function of cytoplasm.
A
Site of cellular reactions
12
Q
Function of mitochondria.
A
Site of aerobic respiration.
13
Q
Function of nuclei.
A
- Contain genetic material.
- Control cellular activity.
14
Q
Function of chloroplasts.
A
Site of photosynthesis using light absorbed by chlorophyll.
15
Q
Function of plasmids.
A
Carry genes that provide genetic advantages.
16
Q
Function of ribosomes.
A
Site of protein synthesis
17
Q
What can be used to judge the relative size/area of sub-cellular structures?
A
Eyepiece graticule with stage micrometer under a microscope.
18
Q
Sperm cell adaptations.
A
- Tail: for movement
- Mitochondria: provides energy for movement.
- Acrosome: contain enzymes to penetrate the egg.
- Haploid nucleus: contain genetic material
19
Q
Nerve cell adaptations.
A
- Dendrites: connect to and receive impulse from other neurones/nerve cells.
- Myelin sheath: insulates axon to speed up the transmission of impulses.
- Long axon: allows electrical impulses to be transmitted around the body from the central nervous system.
20
Q
Muscle cell adaptations.
A
- Protein filament arrangement: allows them to slide over each other to produce muscle contraction.
- Mitochondria: provide energy for muscle contraction.
- Merged cells in skeletal muscles: allows muscle fibres to contract in unison.
21
Q
Root hair cell adaptations.
A
- Tube-like protrusions (RHC): increase surface area for absorption.
- Long and penetrates soil (RHC): decrease distance substances must move; reach wider area.
- Thin walls: reduce restriction for water absorption (short diffusion pathway).
- Mitochondria: provide energy for active transport.
22
Q
Xylem cells adaptations.
A
- No margins between vessels: provide continuous route for water flow.
- Dead cells/no components: no interruption to transporting substances.
- Lignin-thickened walls: strengthen structure and prevent collapse
23
Q
Phloem cells adaptations.
A
- Companion cells: provide energy from mitochondria for substance transport.
- Sieve plates: allow sugars and amino acids to flow through up and down.
24
Q
Cell differentiation
A
Process by which a cell becomes specialised
25
Importance of cell differentiation.
Enables cells to acquire sub-cellular structures that enable it to perform specific functions - can be used in the growth/development of an organism, to repair and replace dead or damaged cells.
26
Time of differentiation in most animal cells.
Early in their life cycle
27
Time of differentiation in majority of plant cells.
Retain ability throughout their entire life cycle.
28
Compare electron microscope to light microscope.
- Higher resolution compared to light microscope.
- Greater magnification compared to light microscope.
29
Advantages of light microscopes.
- Inexpensive
- Portable
- Easy to use
- Observe both dead and living specimen.
30
Disadvantages of electron microscopes.
- Expensive
- Large so less portable
- Requires training
- Only dead specimen can be observed.
31
Types of electron microscopes.
- Scanning electron microscope (3D imaging)
- Transmitting electron microscope (2D imaging)
32
How electron microscopy increased understanding of sub-cellular structures.
- Cells could be studied in much finer detail.
- Scientists could to see and understand more sub-cellular structures.
- Scientists could develop more accurate explanations about how cell structure relates to function.
33
Equation for magnification
Magnification = image size ÷ actual object size
34
Name for bacterial division.
Binary fission
35
Frequency of bacterial division.
Once every 20 minutes if conditions (temperature and nutrients) are suitable and sufficient.
36
Places for bacteria to be grown.
- Nutrient broth solution
- Colonies on an agar gel plate
37
Requirement for the investigation of disinfectant and antibiotic action.
Uncontaminated culture of microorganisms.
38
Describe how to prepare uncontaminated cultures using aseptic techniques.
1. Use pre-sterilised plastic Petri dish, or sterilise glass Petri dish and agar gel with an autoclave.
2. Pour sterile agar gel into Petri dish and let it set.
3. Sterilise inoculating loop by passing through Bunsen burner flame.
4. Use inoculating loop to dip into solution and make streaks on agar surface.
5. Secure lid on Petri dish using tape and label accordingly.
6. Incubate the culture upside down at 25ºC in school laboratory.
39
Reason why Petri dish and culture media must be sterilised before use.
To kill any present bacteria.
40
Reason why inoculating loops must be sterilised by passing them through a flame.
To kill any bacteria present on loop.
41
Reason why the lid of the Petri dish should be secured with adhesive tape and stored upside down.
- Stop bacteria in air contaminating the culture whilst making sure no anaerobic bacteria grow.
- Prevent condensation forming and dripping onto colonies.
42
Reason why, in school and college laboratories, cultures should be incubated at a maximum temperature of 25°C.
Harmful pathogens are less likely to grow at this temperature.
43
Equation for cross-sectional areas of colonies.
πr2
44
Equation to calculate the number of bacteria in a population after a certain time if given the mean division time.
1. _Calculate how many times the bacteria divides in given time._
(60 ÷ mean division time) × end time given.
2. _Calculate the number of bacteria in the population._
Bacteria at the end of time period = Bacteria at the beginning × 2number of divisions
