Cells - questions

Question 1

Role of enzymes

Answer 1

Biological catalysts which speed up biochemical reactions in an organism.

Question 2

Description of the structure of enzymes including term active site

Answer 2

Enzymes are proteins made up of amino acids linked together in one or more polypeptide chains. Enzymes have an active site that joins with a specific substrate

Question 3

Explain why the shape of the enzyme active site is needed for a reaction to occur

Answer 3

The shape of the active site is critical as is the part of the active site that enable it to bind to a single type of substrate, so that the enzyme is able to continue to catalyse reactions

Question 4

Describes inhibitors effect on enzyme

Answer 4

Inhibitors are compounds which modify the catalytic properties of the enzyme and, therefore, slow down the reaction rate, or in some cases, even stop the reaction

Question 5

Describes the function of the cell cycle

Answer 5

The function of the cell cycle is to duplicate DNA in the chromosomes and then segregate the copies into two genetically identical daughter cells

Question 6

Describes how one of the stages of the cells is involved

Answer 6

During the G1 stage the cell increases in size, in the S stage the cell copies its DNA, the cell prepares to divide during the G2 stage, and it divides during mitosis

Question 7

Give equation for photosynthesis

Answer 7

carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll)

Question 8

Describe the purpose of photosynthesis

Answer 8

Photosynthesis is the process of plants using sunlight, water, and carbon dioxide to produce glucose and oxygen

Question 9

Describe light dependent phase

Answer 9

Light energy is absorbed by the pigment chlorophyll. This light energy splits the water molecule into oxygen and hydrogen. Hydrogen ‘goes to the’ light-independent process, while oxygen is excreted as a waste product (via stomata on leaves).

Question 10

Describe light independent phase

Answer 10

In the light independent phase, carbon dioxide and Hydrogen are joined together to create glucose. This phase does not require light

Question 11

Describes how water availability affects rate of photosynthesis

Answer 11

Because water is a reactant in the light dependent phase, water availability can affect rates of photosynthesis as there is less hydrogen. This means that the light independent phase will not be able to happen and glucose will not be created.

Question 12

Define osmosis

Answer 12

the movement of water across the membrane from an area of higher water concentration to lower water concentration.

Question 13

Give equation for aerobic respiration

Answer 13

glucose + oxygen → 36ATP + carbon dioxide + water

Question 14

Describe the purpose of respiration

Answer 14

to provide oxygen to the cells at a rate adequate to satisfy their metabolic needs

Question 15

Draw and label mitochondria

Answer 15

refer to diagram

Question 16

Describe an adaptation of the mitochondria

Answer 16

Mitochondria have a double membrane structure, with an inner layer with many folds to create a high surface area. This provides more space for more metabolising proteins and therefor they are able to create more energy at one time.

Question 17

State a cell function that requires energy

Answer 17

Active transport requires energy to move molecules from an area of low concentration to an area of high concentration

Question 18

Define diffusion

Answer 18

The movement of materials from an area of high concentration to an area of low concentration

Question 19

Define facilitated diffusion

Answer 19

A form of passive transport where molecules move across the cell membrane through the membrane proteins

Question 20

Define active transport

Answer 20

The movement of molecules from an area of low concentration to an area of high which requires energy

Question 21

What are factors that affect enzymes

Answer 21

Enzymes are affected by pH and temperature.
A low or high pH will disrupt the hydrogen bonds of the enzyme’s protein and cause the enzyme to denature. This means the active site will change shape and not fit with the specific substrate.

At very low temperatures the enzyme action is slow and at high temperatures the enzyme may become denatured which makes their active site change shape and not fit with its specific subsrate.

Question 22

Define anaerobic respiration

Answer 22

Anaerobic respiration occurs in the cytoplasm of the cell. It does not require oxygen. In most cases, during anaerobic respiration, glucose is broken down into carbon dioxide or ethanol.

Question 23

Define chloroplast

Answer 23

A chloroplast is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells

Question 24

Relate structure of chloroplast to efficient photosynthesis

Answer 24

Part of the photosynthesis reactions occur in an internal membrane within the organelle. The chloroplast contains many of these internal membranes, making photosynthesis very efficient

Question 25

Describe DNA replication

Answer 25

DNA replication is the process by which the genome’s DNA is copied in cells. Before a cell divides, it must first copy (or replicate) its entire genome so that each resulting daughter cell ends up with its own complete genome.

Question 26

Explain why DNA replication is necessary for cell cycle

Answer 26

DNA replication ensures that each daughter cell gets a copy of the genome, and therefore, successful inheritance of genetic traits

Question 27

Define mitosis

Answer 27

The purpose of mitosis is to produce two identical cells for
growth of the organisms AND the repair of tissues / replacement of cells.

Question 28

Explain why mitosis is necessary for cell cycle

Answer 28

after a cell reaches a certain size, it must carry out mitosis to produce two new
smaller cells that have a larger surface area:volume ratio and can transport materials at a
fast-enough rate to support cellular function.