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Biology GCSE > B2 > Flashcards

B2 Flashcards

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1
Q

What is diffusion?

A

Diffusion is the net movement of particles from a region of high concentration to low concentration down the concentration gradient.

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2
Q

How do you increase rate of diffusion?

A
  • Decrease distance particles must move
  • Increase concentration gradient
  • Increase surface area (more space for diffusion)
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3
Q

What is osmosis?

A

Net movement of water particles from an area of high water potential to low water potential, across a semi-permeable membrane down the concentration gradient.

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4
Q

What is active transport?

A

Movement of particles across a membrane against the concentration gradient (low concentration to high).

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5
Q

Key features of active transport

A
  • Requires ATP
  • Transported against concentration gradient
  • Carrier proteins are used
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6
Q

Examples of active transport.

A
  • Plants take up nutrients from the soil which has a lower concentration of nutrients than in the root hair cells
  • Nervous system, carrier protein pumps sodium ions out and potassium ions in (sodium potassium pump)
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7
Q

What is mitosis?

A
  • process of body cells dividing to produce 2 identical daughter cells.
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8
Q

Explain the period of cell growth.

A

G1 - Gap 1 - cell grows, new cell structures and proteins made
S - DNA replication - DNA unzips, free nucleotides attach to the strands (complementary base pairing)
G2 - Gap 2 - cell grows and protein needed for cell division is made.
M - mitosis

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9
Q

Explain the process of mitosis.

A
  • DNA replicates
  • Chromosomes line up in the centre of the cell.
  • Cell fibres pull the chromosomes apart to the opposite ends of the cell.
  • Membranes form around the two sets of chromosomes (new nuclei)
  • Cytoplasm divides and there are now two genetically identical cells.
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10
Q

Adaptations of a sperm cell.

A
  • Acrosome - in the head of sperm, digestive enzymes which break down the outer layers of the ovum to transfer genetic information.
  • Mitochondria - lots of it, so lots of respiration and energy so allow the flagellum to move.
  • Flagellum - tail to swim
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11
Q

Adaptations of a fat cell.

A
  • Specialized to store fat so that animals can survive when food is short.
  • Insulation provider.
  • layer of cytoplasm around reservoir to allow cell expansion.
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12
Q

Adaptations of a red blood cell.

A
  • Biconcave disc to increase surface area to allow quicker rate of diffusion (gaseous exchange).
  • No nucleus to allow it to be packed full of haemoglobin, this protein binds to oxygen.
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13
Q

Adaptations of ciliated cells.

A
  • Cilia on cells sweep mucus away from your lungs and back of throat.
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14
Q

Adaptations of palisade cells.

A
  • Found near surface of cell and are full of chloroplast to allow light absorption to be quicker and photosynthesis can occur.
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15
Q

What are stem cells?

A
  • Undifferentiated cells that can differentiate into any cell and perform its function.
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16
Q

Types of stem cells

A

Embryonic - found in embryos and can differentiate into any cell.
Adult - found in bone marrow and can differentiate into cells of their tissue of origin.

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17
Q

Stem cells in plants.

A
  • Meristems - only part of the plant that can divide my mitosis
  • Found in roots and shoots
  • Differentiate into any type of cell in the plant and last the life of the plant.
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18
Q

Why is it harder to exchange surfaces in multi-cellular organisms?

A
  • Poor surface area:volume ratio.
  • Substances have to travel large distances to reach the desired target and won’t reach the cells demand
  • They have adapted exchange surfaces to increase their SA:V ratio.
19
Q

Lung adaptations for gas exchange.

A
  • To exchange gas (transfer oxygen to blood and remove waste CO2), the lungs have millions of air sacs called alveoli.
  • Alveoli have - large surface area, thin walls, moist lining to dissolve gases, good bloody supply.
20
Q

Small intestine adaptations.

A
  • The small intestine is where dissolved food molecules are absorbed.
  • They have millions of tiny finger-like projections called villi.
  • They increase the surface area to speed up diffusion, a good blood supply to assist quick absorption and a single layer of surface cells.
21
Q

What is the structure of a double circulatory system?

A
  • Contains the heart, blood vessels and blood.
  • Deoxygenated blood pumped from the heart to the lungs to be oxygenated.
  • Oxygenated blood returns to the heart and is pumped to the necessary organs of the body to give oxygen and glucose to cells.
  • Carbon dioxide enters the blood
  • Deoxygenated blood returns to the heart to be pumped the lungs to be oxygenated and for carbon dioxide to be removed.
22
Q

What are the tree blood vessels?

A

Arteries - carry blood away from the heart.
Veins - carry blood back to the heart
Capillaries - Exchange of materials at tissues.

23
Q

Structure of an artery

A
  • Blood is pumped away from the heart at high pressure so the walls are thick, strong and elastic (outer wall and layer of muscle and elastic fibres).
  • Small lumen to allow pressure to increase.
  • Arteries branch into arterioles.
24
Q

Structure and adaptations of a capillary

A
  • Arterioles branch into capillaries
  • Network of capillaries - capillary bed
  • Carry blood close to every cell and exchange substances.
  • One layer thick permeable wall to allow for quick diffusion.
  • Capillaries branch into venules.
25
Q

Structure, function and adaptations of veins.

A
  • Venules join up to make valves
  • Blood is at lower pressure, no thick walls but larger lumen.
  • Valves to prevent backflow of blood.
26
Q

Blood flow at the right side of the heart.

A

Deoxygenated blood enters at the vena cava (superior/inferior) > right atrium > (atria contract pushing blood into the right ventricle) tricuspid valve > right ventricle > (ventricle contracts) pulmonary valve > pulmonary artery to the lungs.

27
Q

Blood flow at the left hand side of the heart.

A

Oxygenated blood from the lungs through the pulmonary vein > left atrium > atria contract > bicuspid valve > left ventricle > aortic valve > aorta > blood to the rest of the body.

28
Q

What are the 4 components of blood?

A

Plasma
Red Blood Cells
White Blood Cells
Platelets

29
Q

What is in plasma?

A
  • Straw coloured liquid (where blood cells float)
  • 90% water
  • Digested food products
  • Urea, hormones, antibodies and waste (e.g. CO2)
30
Q

What are white blood cells.

A

White blood cells - contain nucleus, fight diseases: making antibodies or engulfing microorganisms.

31
Q

What are plateles?

A

Tiny structures that help blood clotting.

32
Q

What makes up the vascular bundle system and what are their basic functions?

A

Xylem - transport water and mineral ions (via active transport) from the roots to stems, leaves and flowers (up the plant).

Phloem - transport soluble food molecules and dissolved sugars made during photosynthesis from the leaves. Called translocation. Sugars taken to the meristem to make new plant cells.

33
Q

Structure of a xylem.

A
  • Made of dead xylem cells.
  • No cell walls
  • One way flow of water and dissolved mineral ions
  • Cell walls are strengthened with lignin, stiff and strong giving the plant support.
34
Q

Structure of a phloem.

A
  • Made of columns of living cells
  • They have perforated sieve plates to allow dissolved sugar, water and foods through.
  • Transport both up and down the plant.
35
Q

How do the vascular bundles provide support?

A
  • Network at leafs that support soft leaf tissue
  • Situated around the stem, to provide strength and resist bending in the breeze.
  • Centre of the root to anchor it.
36
Q

What is the transpiration stream?

A
  • Loss of water through the plants leaves and the uptake of water from the roots through osmosis and the xylem tissue.
  • Constant flow of water called the transpiration stream.
37
Q

How is water lost from leaves?

A
  • In bright conditions (during the day) and during photosynthesis, the guard cells take up water and swell to become turgid opening the stomata.
  • Water then diffuses out of the leaf and water is lost.
38
Q

How do stomata control water loss?

A
  • Most stomata is found on the underside of the leaf = lack of light = stay flaccid and won’t open
  • Waxy cuticle at the top of the leaf to prevent water loss
  • No stomata on the upper epidermis.
39
Q

Factors affecting rate of transpiration.

A

Light intensity
Temperature
Humidity
Air movement (wind)

40
Q

How does light intensity affect rate of transpiration?

A

Increases rate of transpiration as the stomata will open, until all the stomata open and rate of transpiration is at its maximum.

41
Q

How does temperature affect rate of transpiration?

A

Increasing temperature increasing rate of water evaporation increasing the rate of transpiration constantly.

42
Q

How does air movement affect rate of transpiration?

A
  • Air moves over the surface of a leaf taking away water molecules. Faster the air, faster the movement of water molecules, faster the rate of transpiration.
  • Also increases rate of diffusion of water as the concentration gradient is increased as water leaves the leaf.
43
Q

How does humidity affect rate of transpiration?

A

Humidity = concentration of water in the air.

  • Decreasing humidity increases rate of transpiration as the concentration gradient between the leaf and air is increased so water can diffuse out.
  • High humidity = low rate of transpiration.

Biology GCSE (6 decks)

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