Cells and Transport Across Membranes 2023 Biology

Question 1

What is the function of the nucleus?

Answer 1

Contains DNA which controls cellular function by coding for proteins.

Question 2

What is the function of the plasma cell membrane?

Answer 2

Regulates the inputs and outputs of the cell. It does this through a feature called selective permeability

Question 3

What is the function of the ribsome?

Answer 3

Site of protein synthesis.

Question 4

What is the function of cytosol?

Answer 4

Fluid part of the cell where some chemical reactions occur.

Question 5

What is the function of the mitochondria?

Answer 5

Site of aerobic cellular respiration.

Question 6

What are the components of the plasma membrane?

Answer 6

-Phospholipid bilayer
-Protein channel
-Protein pump

Question 7

What type of particles can move directly across the phospholipid bilayer?

Answer 7

Small and uncharged particles such as oxygen and carbon dioxide.

Question 8

What types of particles have to move across the phospholipid bilayer via a protein channel or protein pump?

Answer 8

Large and charged particles; for example, glucose and mineral ions like calcium.

Question 9

What two organelles have double membrane structures?

Answer 9

The mitochondria and chloroplasts.

Question 10

What is the equation of aerobic cellular respiration?

Answer 10

-Glucose and Oxygen > Carbon Dioxide and Water
-If aerobic cellular respiration occurs inside the cell, this means the reactants, glucose and oxygen, need to move inside the cell.
-Whereas, carbon dioxide and water are the waster products of aerobic cellular respiration and need to be excreted out.

Question 11

What is the difference between reactants and products?

Answer 11

-Reactants are the substances at the beginning of the chemical reaction, whereas products are the substances formed by the reaction.

Question 12

What is aerobic cellular respiration?

Answer 12

-Aerobic cellular respiration is a chemical reaction in our cells where food is broken down and turned into energy that cells need to perform their life functions (e.g protein synthesis)
-The mitochondria is the site of aerobic cellular respiration

Question 13

What is role of a sperm cell?

Answer 13

-Sperm cells are a male reproductive cell
-They have a tail and many mitochondria which propels the cell for its function: to reach an ovum (egg cell) and fuse with it.

Question 14

What is the role of a muscle cell?

Answer 14

-Muscle cells allow for contraction that changes the length and shape of the cell. This allows muscles to produce force and motion.
-Muscle cells have many mitochondria to allow them to respond quickly to the need for doing work

Question 15

What are specialised cells?

Answer 15

-Specialised cells are cells that have developed certain characteristics to perform a particular function

Question 16

What are some plant cell ONLY organelles?

Answer 16

-Large, permanent vacuole
-Cell wall
-Chloroplast

Question 17

What is the function of the chloroplasts?

Answer 17

Site of photosynthesis

Question 18

What is the function of the cell wall?

Answer 18

Provides support and structure to the cell.

Question 19

What is function of the large permanent vacuole?

Answer 19

Stores cell sap

Question 20

What organelles do ANIMAL cells contain?

Answer 20

-Nucleus
-Cytosol
-Plasma cell membrane
-Ribosomes
-Mitochondria

Question 21

What is the equation for photosynthesis?

Answer 21

Water + Carbon dioxide >(Chlorophyll/sunlight/excess water)> Glucose + Oxygen

Question 22

What is the function of a palisade cell?

Answer 22

-Palisade cells are plant cells located at the top of the leaf. They are elongated and have many chloroplasts. These chloroplasts absorb a major portion of the light energy used by the leaf

Question 23

What is the function of the root hair cell?

Answer 23

-The function of the root hair cell is to collect water and mineral ions present in the soil and take them through the roots to the rest of the plant
-The root hair cell is underground and therefore doesn’t carry out photosynthesis/have chloroplasts
-These cells are adapted for the intake of water and mineral ions so they have “root hairs” to increase the surface area of the membrane.

Question 24

Define diffusion

Answer 24

[Diffusion is the net movement of particles from a high concentration to a low concentration/down a concentration gradient.]
-This is a result of the random movements of the particles of a gas or liquid which have kinetic energy
-The overall or net movement is a passive process (doesn’t require energy)

Question 25

What are the features of exchange surfaces that make diffusion more efficient?

Answer 25

1. Short diffusion distance ( thin membranes for substances to move across)
2. Large surface area ( more membrane for diffusion to occur across)
3. Good blood supply (to maintain concentration gradient)
4. Moist exchange surface (dissolves gases more easily)

Question 26

What happens when a concentration gradient is increased?

Answer 26

As the concentration gradient increases, the rate of diffusion also increases.

Question 27

How do most animals obtain their supply of oxygen if diffusion is to slow?

Answer 27

Through breathing. Animals have a circulatory system which will transport oxygen around the body.

Question 28

What substances would need to pass through the plasma cell membrane?

Answer 28

-Carbon dioxide
-Water
-Glucose
-Oxygen
-Mineral ions

Question 29

What are some examples of mineral ions?

Answer 29

Various mineral ions are important of chemical reactions within the cell
-Calcium is vital for bone development
-Iron is required to transport oxygen in red blood cells

Question 30

Define facilitated diffusion

Answer 30

-Facilitated diffusion is the net movement of particles from a high concentration to a low concentration/down a concentration gradient, through a protein channel

Question 31

Define active transport

Answer 31

-Active transport is the movement of dissolved substances from a low concentration to a high concentration/ against a concentration gradient, through a protein pump, using ATP

Question 32

What is ATP?

Answer 32

ATP (Adenosine Triphosphate) is the universal energy currency of the cell. Energy within the cell can be released when ATP is broken down into ADP and P(i)

Question 33

How would glucose move into the cell for aerobic cellular respiration?
Outside=13% Inside=37%

Answer 33

-Active transport has occurred
-Glucose has moved from a low concentration outside of the cell (13%), through the protein pump, to a high concentration inside of the cell (37%), using ATP.

Question 34

How would carbon dioxide exit a plant cell?
Outside=0.4% Inside=23%

Answer 34

-Diffusion has occurred
-Carbon dioxide has moved from a high concentration inside the cytosol of the plant cell (23%), through the phospholipid bilayer, to a low concentration outside of the plant cell (0.4%)

Question 35

Why are cells small?

Answer 35

It is all about surface area : volume ratio
-A larger surface area to small volume allows for more efficient diffusion.
-Cells may increase their SA: V ratio by having:
-Long thing shape/ elongated shape e.g nerve cells
-Folding membrane of the object/cell membrane e.g villi of the lining in the small
intestines
-Plant cells are much larger than animal cells and they have a large permanent vacuole
which pushed the organelles to the edge of the cell where they get regular access to
resources
TEMPERATURE ALSO AFFECTS THE RATE OF DIFFUSION

Question 36

What is scaffold for describing graphs?

Answer 36

-As ( IV-x axis label) increases/decreases, the (DV-y axis label) increases/decreases/remains the same(plateus)

Question 37

https://www.google.com/search?q=Number+of+bubbles+produced+by+plant+x+in+various+depths+of+water&sxsrf=APwXEdf4NyrKfSmY0FM3vGJt-Eq5E3Z9yA:1685266286985&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiS0IyT2pf_AhXPXmwGHZ2wDp0Q_AUoAXoECAEQAw&biw=1920&bih=933&dpr=1#imgrc=550ktu2P0Pr_XM

DESCRIBE THE GRAPH

Answer 37

As the depth increases from 2m to 10m the bubbles per minute increases from 29 to 45.

The optimum( maximum) bubbles/min is 45.

As the depth further increases from 10m to 37m, the bubbles per minute decreases from 45 to 8.

Question 38

Define osmosis

Answer 38

Osmosis is the net movement of water molecules from a high concentration of water molecules, through a partially permeable membrane, to a low concentration of water molecules.

Question 39

Describe how water would move in and out of the red blood cell:
Inside=23% Outside=100%

Answer 39

-Osmosis has occurred
-Water has moved from a high concentration outside of the red blood cell, through a partially permeable membrane, to a low concentration inside the cytosol of the cell.

Question 40

What happens when an animal cell gains water?

Answer 40

-Lysis (cell swells and eventually bursts)

Question 41

What happens when an animal cell loses water?

Answer 41

-Crenates (cell becomes shrivelled)

Question 42

What happens when a plant cell loses water?

Answer 42

-Plasmolysis (cell wall of plant cell stays the same however the plasma cell membrane becomes shrivelled up)

Question 43

What happens when a plant cell gains water?

Answer 43

-Turgid ( plant cell becomes more round as it has gained so much water. It doesn’t burst due to cell wall)
-This turgid pressure helps keep plants upright. When plants wilt, is is because they don’t have lots of water/ their cells aren’t turgid.

Question 44

What is a solution?

Answer 44

-Each solution has a solvent (water) and a solute (dissolved sugars and salts).
-A concentrated solution has a high number of solute molecules compared to solvent molecules
-A dilute solution has a high number of solvent molecules compared to solute molecules

Question 45

Describe what has happened TO THE CELL:
Solution (100% H2O) Cell (40% H2O)

Answer 45

-Osmosis has occurred
-Water has moved from a high concentration in the solution (100%), through a partially permeable membrane, to a low concentration in the cytosol of the cell (40%)
-As a result, the cell becomes lysed.
*REMEMBER TO READ THE QUESTION {TO THE CELL}

Question 46

What happens when a plant cell becomes turgid?

Answer 46

-The cell wall is fully permeable so water enters the plant cell through the partially permeable plasma membrane
-The cell membrane is pushed against the cell wall by the expanding cytosol and vacuole
-The cell is described as turgid
-Turgid cell pressure (turgor pressure) holds young plants up

Question 47

What happens when a plant cell becomes plasmolysed?

Answer 47

-If placed in a concentrated solution, water will leave the plant cell through the partially permeable membrane.
-The cell membrane pulls away from the cell as the cytosol and vacuole shrink
-The cell is described as plasmolysed
-Plasmolysed cells do not exert pressure so young plants wilt

Question 48

Do gases move faster than liquids in terms of diffusion.

Answer 48

Yes

Question 49

Examples of exchange surfaces.

Answer 49

-Alveoli; Oxygen diffuses from the air, through the lining of the lungs and into the bloodstream.
-Leaf; Carbon dioxide diffuses into leaves and enters leaf cells by diffusion
-Placenta; The placenta is the gas exchange surface for the foetus. It is also where the food and wastes are exchanged.
-Villi; Most digested carbohydrates move by a form of diffusion into the capillaries while the products of fat digestion diffuse into the lacteals
-Protozoa (single celled organisms); Some single celled animals e.g amoeba, rely on diffusion for all their needs.

Question 50

Do heavier molecules diffuse slower?

Answer 50

Yes. The same is true for the reverse ( lighter molecules)

Question 51

Why does diffusion distance place a limit on cell size?

Answer 51

The greater the distance that a substance must travel, the slower the rate of diffusion. This places an upper limitation on cell size. A large, spherical cell will die because nutrients or waste cannot reach or leave the centre of the cell. Therefore, cells must either be small in size or flattened.

Question 52

Why is diffusion important in biology?

Answer 52

Diffusion is important to cells because it allows them to gain the useful substances they require to obtain energy and grow, and lets them get rid of waste products.