B2-Scaling Up

Question 1

1.) Describe the stages of Mitosis.

Answer 1

1.) Interphase: Gap phase 1 - This is when the cell grows and proteins are made, Synthesis - When the DNA replicates, Gap phase 2 - keeps growing and proteins are made for cell division.
Prophase: DNA uncoils and centrioles appear.
Metaphase: Centrioles move to the poles and chromosomes lineup on the equator.
Anaphase: Spindal fibres grow from the centrioles and attach to the centromeres and pull apart the sister chromatids.
Telophase: The chromosomes turn into DNA to make two nuclei.
Cytokinesis: The cytoplasm splits.

Question 2

2.) Explain why the cells in mitosis are genetically identical.

Answer 2

2.) Because the DNA duplicates in interphase and each arm of the chromosome is genetically identical meaning in anaphase when the sister chromatids are split each genetically identical sister chromatid goes into each nuclei and that means when it splits it goes into two genetically identical nuclei

Question 3

3.) Give an example of a cell that is specialised to carryout a particular function.

Answer 3

3.) Palisade cells - they are packed with chloroplasts and have a tall shape which increases their surface area to volume area allowing for maximum photosynthesis and storage of substances.
Sperm cells - Contain male DNA which is needed in reproduction, they have long tails which allow for movement, they contain mitochondria needed for energy and they have special enzymes at their tips which digest the egg cell membrane.

Question 4

4.) Give two differences between adult and embryonic stem cells.

Answer 4

4. )a.) Embryonic stem cells are pluripotent so they have the ability to specialise into any cell as they are undifferentiated, germ cells / Adult stem sells are multi-potent so are somewhat specialised.
   b. ) Adult stem cells are found in certain tissue such as bone marrow and are differentiated however embryonic stem cells are found in embryos.

Question 5

5.) Where are stem cells found in plants.

Answer 5

5.) Meristem tissue - areas where the plant is growing e.g stem, roots, shoots and leaves.

Question 6

6.) Give three substances that move across cell membranes during diffusion.

Answer 6

6. )a.) Food such as glucose and amino acids
   b. ) Water
   c. ) Oxygen

Question 7

7.) Explain how active transport is different from diffusion.

Answer 7

7.) Active transport is the net movement of substances against the concentration gradient using ATP from respiration whereas diffusion is the net movement of particles with the concentration gradient.

Question 8

8.) Explain the terms hypotonic, hypertonic and isotonic and what this means in plants.

Answer 8

8. )a.) Hypotonic solution is where the solution has more solvent than solute so the solute moves into the cell in plants this is called turgid in plants and lysis in animals.
   b. ) Hypertonic solution is where the solution has more solute than solvent so the solvent moves from the cell to the solution and in plants this is called plasmolysed in animals this is called crenated
   c. ) Isotonic solution mean there is equal solute and solvent so the solvent passes to and from the cell keeping an equilibrium in animals this is called normal in plants is flaccid.

Question 9

9.) What is a partially permeable membrane, give examples.

Answer 9

9.) Its a membrane with very small holes allowing only some things to diffuse across it.

Question 10

10.) Liquid A and liquid B are separated by a partially permeable membrane. There is a net movement of water from liquid B to liquid A. Which liquid has the highest water potential?

Answer 10

10.) At the start it was liquid B but because it diffused they both have the same water potential.

Question 11

11.) If potato cylinders are placed in a solution with a higher water potential than the cylinders what will happen to the mass of the cylinders?

Answer 11

11.) The mass of the cylinders would increase as water moves into the cylinders.

Question 12

12.) Give three factors that effect the movement of substances.

Answer 12

12. )a.) surface area to volume ratio
    b. ) Temperature
    c. ) Concentration gradient

Question 13

13.) Explain why single celled organisms don’t require specialised exchange surfaces and transport systems to exchange substances.

Answer 13

13.) Because they already have a large surface area to volume ratio so they can exchange enough substances to be able to supply the cell with what it needs and the path for diffused substances it short.

Question 14

14.) Give examples of specialised exchange surfaces found in animals; plants and explain how it is adapted to maximise the exchange of substances.

Answer 14

14. )a.) Lungs they have a large surface are due to the alveoli and bronchiole so allow fro rapid diffusion. Also they have thin walls, moist lining and a good blood supply allowing for rapid diffusion. The intestine has a large surface area due to the villi, single layer of surface cells and a good blood supply. Other exchange surfaces include the skin and placenta.
    b. ) Leaves are broad so have a large surface are needed for diffusion. They are thin so gases only have to travel a short distance. Air spaces in the spongy layer allow a large surface area to volume ratio and greater gas exchange. Stomata allow for the diffusion of gas and water.

Question 15

15.) Give two substances that a plant takes in via its root hairs.

Answer 15

15. )a.) Water

b. ) Minerals

Question 16

16.) True or false? Human have a single circulatory system.

Answer 16

16.) False. They have a pulmonary system which goes to the lungs (right ventricle to left atrium) and systemic which goes to the body (left ventricle to right atrium.)

Question 17

17.) How many chambers does the human heart have and what are their names

Answer 17

17. )a.) 4

b. ) left atrium, left ventricle, right atrium and right ventricle

Question 18

18.) Is blood in the pulmonary artery oxygenated or deoxygenated.

Answer 18

18.) Deoxygenated

Question 19

19.) Through which vessel does the blood leave the left ventricle from the heart.

Answer 19

19.) Aorta

Question 20

20.) What are the names of the three main types of vessel and what are their characteristics.

Answer 20

20. )a.) Artery - they transport blood away from the heart, have strong elastic wall to withstand the high pressure, lumen is smaller than the walls, elastic fibres and muscle which allow them to spring back.
    b. ) Vein - transport blood toward the heart again elastic fibres but they have a large lumen compared to arteries to allow for the blood to flow at low pressures and they also have valves to stop back flow.
    c. ) Capillaries - they allow for the exchange of materials, carry blood at a lower pressure they have permeable walls one cell thick to allow for diffusion they have a large surface area to volume ratio allowing for better diffusion and they carry blood close to the cells.

Question 21

21.) What is the role of plasma. What does it carry?

Answer 21

21. )a.) It transports substances around the body and is pale yellow
    b. ) Red blood cells, white blood cells, platelets, water, digested food from the gut such as glucose and amino acids, carbon dioxide, Urea, Hormones, Antibodies.

Question 22

22.) What is the role of red blood cells and what are their characteristics?

Answer 22

22. )a.) They transport oxygen around the body by forming oxyhaemoglobin.
    b. ) they are biconcave allowing for a large surface are to volume ratio, contains haemoglobin, they dont have a nucleus so can easily carry oxygen, they are small and flexible so can fit through capillaries.

Question 23

23.) What is it ment by the term translocation?

Answer 23

23.) It is done by the Phloem it allows food substances to go up and down the plant to growing and storage tissues.

Question 24

24.) What does the xylem and the phloem carry?

Answer 24

24. )a.) Xylem - It transports water and minerals from the roots to the shoots.
    b. ) Phloem - It transports food substances around the plant.

Question 25

25.) What are the characteristics of the xylem and the phloem.

Answer 25

25. )a.) Xylem - dead cells with no end walls and a hole down the middle, strong stiff walls for support made of cellulose and lignin.
    b. ) Phloem - living cells with perforated end plates which allow for diffusion, these cells dont have nuclei so rely on companion cells to keep them alive.

Question 26

26.) What are the three factors of transpiration? and how do they effect it?

Answer 26

26.)a.) Light intensity - with increased light mean the stoma open wider to allow light in for photosynthesis meaning they transpire more as more water ca be evaporated.
b.) Temperature - The hotter it is the more water that is evaporated from the leaf the more the plant transpires.
c.) Air movement - the more wind means that it blows the water off the plant causing more to transpire due to osmosis to keep and equilibrium.
d*.) Humidity - the more humid it is the less is transpired as the concentration gradient is less.

Question 27

27.) Where can the stomata found.

Answer 27

27.) On the underside of the leaf.

Question 28

28.) label the cross section of a leaf.

Answer 28

28.) from top to bottom it is:
waxy cuticle, upper epidermis, palisade layer, spongy layer with xylem and phloem, lower epidermis, stomata and guard cells.

Question 29

29.) How do the stomata’s open.

Answer 29

29.) The guard cells are turgid when they are opened meaning they have an increase of water in their cells and they close when they are flaccid.

Question 30

30.) Draw a diagram showing how a potometer can be used to investigate the rate of transpiration.

Answer 30

30.) Plant, reservoir of water, tubing, ruler, beaker of water and an air bubble

Question 31

31.) What is transpiration and why is it advantageous?

Answer 31

31. )a.) It is the process in which plants take up water because water is being evaporated and lossed.
    b. ) It allows substances for photosynthesis and it keeps the plants cool.

Question 32

32.) What is diffusion

Answer 32

32.) It is the net movement of substances across a membrane down the concentration gradient.

Question 33

33.) What is osmosis

Answer 33

33.) It is the diffusion of water.

Question 34

34.) What is active transport?

Answer 34

34.) It is the net movement of substances across a membrane against the concentration gradient using ATP from respiration.

Question 35

35.) How does the cross-sectional area of vessels effect blood flow?

Answer 35

35.) As the cross-sectional area increases the mean velocity decreases.