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Biology > Chapter 1 Cells > Flashcards

Chapter 1 Cells Flashcards

1
Q

What is the formula for magnification?

A

Magnification=size of image/size of real object

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2
Q

What are the advantages and disadvantages of light microscopes?

A

They are relatively cheap,can be used almost anywhere e.g. schools and can magnify live specimens.
Their magnification is not as high as an electron microscope.
Limited resolution

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3
Q

What are the advantages and disadvantages of an electron microscope?

A

Advantages- they have a high magnification and high resolution
Transmission electron microscope allows you to see in 3D but has a lower magnification.

Disadvantages- very expensive,large and have to be kept in special temperature pressure and humidity controlled rooms.

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4
Q

What is the nucleus?

A

The nucleus controls all the activities of the cell and is surrounded by the nuclear membrane. It contains the genes on the chromosomes that carry out instructions for making the proteins needed to build new cells or new organisms.

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5
Q

The cytoplasm

A

A liquid gel in which the organelles are suspended and where most of the chemical reactions needed for life take place.

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6
Q

Cell membrane

A

Controls the passage of substances such as glucose and mineral ions into the cell. It also controls the movement of substances such as urea and hormones out of the cell.

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7
Q

Mitochondria

A

Structures in the cytoplasm where aerobic respiration takes place, releasing energy for the cell. They are very small.

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8
Q

Ribosomes

A

Where protein synthesis takes place, making all the proteins needed in the cell.

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9
Q

Algae

A

Algae are simple aquatic organisms. They make their own food by photosynthesis and have many similar features to plant cells.

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10
Q

What do all plant and algal cells have?

A

They have a cell wall made of cellulose that strengthens the cell and gives it support.

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11
Q

What are chloroplasts?

A

Chloroplasts are found in all the green parts of a plant. They are green because they contain the green substance chlorophyll. Chlorophyll absorbs light so the plant can make food by photosynthesis . Root cells do not have chloroplasts because they are underground and do not photosynthesise.

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12
Q

A permanent vacuole

A

A permanent vacuole is a space inside the cytoplasm filled with cell sap. This is important for keeping the cells rigid to support the plant

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13
Q

Eukaryotic cell

A

Eukaryotic cells all have a cell membrane, cytoplasm, and genetic material that is enclosed in the nucleus.

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14
Q

Examples of an eukaryotic cell

A

Animal and plant cells

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15
Q

What is genetic material?

A

Genetic material is a chemical called DNA and this forms structures called chromosomes that are contained within the nucleus.

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16
Q

What do prokaryotic cells consist of?

A

Cytoplasm and cell membrane surrounded by a cell wall. The

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17
Q

What is a prokaryotic cell

A

In prokaryote cells, the genetic material (DNA) is not enclosed in a nucleus.

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18
Q

In prokaryotic cells where is the genetic material?

A

The bacterial chromosome is a single loop DNA loop found in the cytoplasm. They may also contain extra small rings of DNA

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19
Q

Slime capsule

A

Some bacteria have a protective slime capsule around the outside of the cell wall.

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20
Q

Flagellum

A

Some types of bacteria have at least one flagellum, that is a long protein strand that lashes about. These bacteria use their flagella to move themselves around.

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21
Q

Nerve cells

A

They are specialised to carry electrical impulses around the body of an animal. They provide a rapid communication system between the different parts of the body.

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22
Q

Nerve cells adaptations

A

.Lots of dendrites to make connections to other nerve cells

. An axon that carries the nerve impulse from one place to another.(very long; the longest axon in your body runs from the base of your spine to your big toe.)

. The nerve endings or synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals they contain lots of mitochondria to provide the energy needed to make the transmitter chemicals.

23
Q

What is the job of a sperm cell?

A

To join with an ovum (egg cell). We call that process fertilisation.

24
Q

Muscle cell

A

They are specialised cells that can contract and relax to move the bones of the skeleton.

25
Q

Adaptations of striated muscle cells

A

. They contain special proteins that slide over each other making the fibres contract

. They contain many mitochondria to transfer the energy needed for the chemical reactions that take place as the cells contract and relax

.They can store glycogen, a chemical that can be broken down and used in cellular respiration by the mitochondria to transfer the energy needed for the fibres to contract.

26
Q

Sperm cells

A

They are usually released a long way from the egg they are going to fertilise. They contain the genetic information from the male parent.

27
Q

Sperm cell adaptions:

A

A long tail whips from side to side to help move the sperm through water or the female reproductive system

the middle section is full of mitochondria which transfer the energy needed for the tail to work

the acrosome stores the digestive enzymes for breaking down the outer layers of the egg

A large nucleus contains the genetic information to be passed on.

28
Q

Root hair cells

A

Root hair cells help the plant to take up water and mineral ions more efficiently

29
Q

Root hair cells adaptations:

A

They greatly increase the surface area available for water to love 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 that transfer the energy need for the active transport of mineral ions into the root hair cells

30
Q

Photosynthetic cells

A

Help to carry out photosynthesis

31
Q

Adaptations of photosynthetic cells:

A

They contain specialised green structures called chloroplasts containing chlorophyll that trap the light needed for photosynthesis

They are usually positioned in continuous layers in the leaves and outer layers of the stem of a plant so they can absorb as much light as possible.

They have a large permanent vacuole that helps keep the cell rigid asa result of osmosis. When lots of these rigid cells are arranged together to form photosynthetic tissue they help support the stem. They also keep the leaf spread out so it can capture as much light as possible.

32
Q

Xylem cells

A

It is the transport tissue in plants that carries water and mineral ions from the roots to the highest leaves and shoots. It is also important in supporting the plant.

33
Q

Xylem cells adaptations:

A

The xylem cells are alive when they are first formed but a special chemical called lignin builds up in spirals in the cell walls. The cells die and form long hollow tubes that allow water and mineral ions to move easily through them, from one end of the plant to another.

The spirals and rings of lignin in the xylem cells make them very strong and help them withstand the pressure of water moving up the plant. They also help support the plant stem.

34
Q

Phloem cells

A

It is a specialised transport tissues that carries the food made by photosynthesis around the body of the plant.

35
Q

Adaptations of phloem cells:

A

The cell walls between the cells break down to form special sieve plates. These allow water carrying dissolved food to move freely up and down the tubes to where it is needed.

Phloem cells lose a lot of their natural internal structures but they are supported by companion cells that help to keep them alive. The mitochondria of the companion cells transfer the energy needed to move dissolved food up and down the plant in phloem.

36
Q

What is diffusion

A

It is the spreading out of particles of any substance. In solution or a gas, resulting in a net movement from and area of higher concentration to an area of lower concentration, down a concentration gradient.

37
Q

What is the rate of diffusion affected by?

A

It is affected by the difference in concentrations, the temperature, and the available surface area.

38
Q

What moves in and out of cells by diffusion?

A

Dissolved substances such as glucose and urea and gases such as oxygen and carbon dioxide move in and out of cells by diffusion.

39
Q

What is osmosis?

A

It is a special case of diffusion. It is the movement of water from a dilute to w more concentrated solution through a partially permeable membrane that allows water to pass through.

40
Q

Isotonic

A

If the concentration of solutes in the solution outside the cell is the same as the internal concentration, the solution is isotonic to the cell

41
Q

Hypertonic

A

If the concentration of solutes in the solution outside of the cell is higher than the internal concentration, the solution is hypertonic to the cell.

42
Q

Hypotonic

A

If the concentration of the solutes in the solution outside the cell is lower than the internal concentration, the solution is hypotonic to the cell.

43
Q

Osmosis in animals

A

Animal cells can be damaged if the concentration outside the cell changes dramatically.

44
Q

What is turgor?

A

When the pressure builds up until no more water can physically enter the cell. Turgor pressure makes the cells hard and rigid which in turn keeps the leaves and stems of the plant rigid and firm.

45
Q

Do plants need the fluid surrounding the cells to be hypotonic or hypertonic to the cytoplasm.

A

They need to be hypotonic. This keeps water moving by osmosis in the right direction and the cells are turgid.

46
Q

What happens if the solution surround the cell is hypertonic.

A

Water will leave the cell by osmosis. The cells will no longer be firm and swollen- they become flaccid-soft as there is no pressure on the cell walls.

47
Q

What happens if more water is lost by osmosis?

A

The vacuole and cytoplasm shrink, and eventually the cell membrane pulls away from the cell wall. This is plasmolysis.

48
Q

Active transport

A

It moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient)

49
Q

What does active transport use?

A

Active transport uses energy released from food in respiration to provide the energy required.

50
Q

What does active transport allow?

A

It allows plant root hairs to absorb mineral ions required for healthy growth from very dilute solutions in the soil against a concentration gradient.

51
Q

What does active transport enable?

A

Sugar molecules used for cell respiration to be absorbed from lower concentrations in the gut into the blood where the concentration of sugar is high.

52
Q

Adaptations for exchanging materials

A

Having a large surface area over which exchange can take place

Having a thin membrane or being thin to provide a short diffusion path

In animals having an efficient blood supply moves the diffusing substances away from the exchange surfaces and maintains a steep concentration (diffusion) gradient

In animals, being ventilated makes gas exchange more efficient by maintaining steep concentration gradients.

53
Q

Examples of adaptations

A

Alveoli

Stomata

Biology (11 decks)

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