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Biology > Cell biology - paper 1 > Flashcards

Cell biology - paper 1 Flashcards

(52 cards)

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1
Q

What is active transport?

A

The movement of substances from a dilute solution to a concentrated solution against the concentration gradient. It requires energy.

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2
Q

Where is active transport required in plants?

A

To allow mineral ions to be absorbed into root hair cells.

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3
Q

Where is active transport required in the body?

A

When sugar molecules are absorbed into blood.

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4
Q

What factors affect the rate of diffusion?

A

Temperature, surface area, difference in concentration.

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5
Q

What is osmosis?

A

Diffusion of water through a partially permeable membrane.

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6
Q

Why do organisms need a large surface area to volume ratio?

A

To allow sufficient transport of molecules in and out of cells.

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7
Q

What is therapeutic cloning?

A

When an embryo is produced with the patient’s genes so that stem cells from the embryo can be used and they won’t be rejected.

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8
Q

What can stem cells be used to treat?

A

Diabetes and paralysis.

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9
Q

What are disadvantages of therapeutic cloning?

A

Transfer of viral infection, religious and ethical issues.

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10
Q

What is a stem cell?

A

An undifferentiated cell that can be used to create more cells of the same type.

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11
Q

What is the function of stem cells from human embryos?

A

They can be cloned and can differentiate into most other human cells.

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12
Q

What is the function of stem cells from adult bone marrow?

A

They can form many types of cells including blood cells.

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13
Q

What is the function of stem cells from meristems?

A

They can differentiate into any type of plant cell throughout its life.

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14
Q

How big is a eukaryotic cell?

A

10-100 micrometers.

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15
Q

What is a eukaryotic cell?

A

A cell with a nucleus. eg: animal and plant cells.

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16
Q

What is a prokaryotic cell?

A

A cell without a nucleus. eg: bacteria cell.

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17
Q

How big are prokaryotes?

A

0.1-5.0 micrometres.

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18
Q

What is the function of the nucleus?

A

Contains DNA.

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19
Q

What is the function of the cell membrane?

A

The cell membrane controls movement of substances in and out of the cell.

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20
Q

What is the function of the mitochondria?

A

Where energy is released through respiration.

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21
Q

What is the function of chloroplasts?

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A

Contains chlorophyll for photosynthesis.

22
Q

What is the function of plasmids?

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A

Small rings of DNA.

23
Q

What is the function of cytoplasm?

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A

Where chemical reactions take place.

24
Q

What is the function of ribosomes?

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A

Site of protein synthesis.

25
What is the function of the vacuole?
Contains cell sap.
26
What is the function of the cell wall?
A rigid layer made of cellulose that strengthens the cell.
27
Describe cell differentiation.
The process during which unspecialized cells take on individual characteristics and reach their mature (specialized) form and function. Animal cells do this at an early stage. Plant cells do this throughout their life.
28
What is the method for RPA1: microscopy?
1) Peel a thin layer of onion and put it on the slide. 2) Add iodine and place the cover slip on top. 3) Put the slide on the stage and look down the microscope. 4) Use the lowest magnification, the coarse focus, and the fine focus to adjust.
29
What is meant by order of magnification?
How many times bigger one thing is than another. 1 order of magnitude = ×10.
30
How do you convert mm, nm, and um?
mm ×1000 = um (micrometers) um × 1000 = nm (nanometers).
31
What is the equation for magnification?
Magnification = size of image ÷ size of real object.
32
How do bacteria multiply?
Simple cell division (binary fission).
33
How and why are bacteria grown?
Bacteria can be grown in nutrient broth or an agar plate. They can be used to investigate antibiotics.
34
What are advantages of electron microscopes?
They have a much higher range of magnification and resolution which allowed scientists to study cells in more detail and understand sub-cellular structures.
35
What is the cell cycle?
1) Cell grows bigger and more mitochondria and ribosomes are produced. DNA replicates and forms copies of each chromosome. 2) Mitosis - one set of chromosomes is pulled to each end of the cell. 3) The cytoplasm and cell membrane divide to form two identical daughter cells.
36
How can the effectiveness of an exchange surface be increased?
- Large surface area - Thin membrane (short diffusion path) - Efficient blood supply - Ventilation.
37
How is the small intestine adapted for exchanging materials?
Villi for large surface area, villi one cell thick (short diffusion path) and a good blood supply.
38
How are lungs adapted for exchanging materials?
Alveoli and capillaries are one cell (short diffusion path). Lots of capillaries - large surface area to volume ratio and good supply of blood to remove and transport gases faster.
39
How are gills adapted for exchanging materials?
Gill filaments (large surface area).
40
How are leaves adapted for exchanging materials?
Stomata (good ventilation).
41
What are the functions and adaptations of sperm cells?
Function: fertilise the egg. Adaptation: tail to swim, lots of mitochondria.
42
What are the functions and adaptations of nerve cells?
Function: carry electrical impulses. Adaptation: branched endings, myelin sheath.
43
What are the functions and adaptations of muscle cells?
Function: allows movement. Adaptation: lots of protein and mitochondria.
44
What are the functions and adaptations of root hair cells?
Function: absorbs mineral ions. Adaptations: large surface area, lots of mitochondria.
45
What is the function and adaptations of the xylem?
Function: carry water from roots to leaf. Adaptations: thick walls, no internal structure.
46
What are the functions and adaptations of the phloem?
Function: carry dissolved sugars. Adaptation: sieve tubes, companion cells.
47
What is the method for RPA3: osmosis?
1) Peel potato and use a cork borer to produce three potato cylinders. 2) Use a scalpel to cut the cylinders at 3cm. 3) Record the mass of each one. 4) Put each one in a test tube with different concentrations of sugar solutions. 5) Leave overnight and then dry them. 6) Measure the length and mass again to calculate percentage change.
48
How do you prepare an uncontaminated culture?
1) Sterilise all petri dishes to kill unwanted microorganisms. 2) Pass an inoculating loop through a flame to sterilise it. Transfer bacteria to plate using it. 3) Secure lid with tape. 4) Put plate upside down in incubator to stop moisture dripping onto bacteria. 5) Keep incubator at 25°C to reduce risk of harmful bacteria growing.
49
What does a cell nucleus contain?
Pairs of chromosomes made of DNA molecules. Each chromosome contains lots of genes.
50
What is the method for RPA2: culturing microorganisms?
1) Clean bench with disinfectant. 2) Sterilise inoculating loop with flame. 3) Open agar plate near flame. 4) Spread bacteria over plate. 5) Put filter paper containing antibiotics on plate. 6) Incubate at 25°C. 7) Calculate area of inhibition using pi × r².
51
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration.
52
How can stem cells from meristems be used?
They are used to produce plant clones quickly and economically for research, horticulture and agriculture. They can also be used to produce plants that are resistant to diseases.

Biology (4 decks)

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