Biology - Friday 7th April

Question 1

What is the difference between Glycogen, Glucose, Glucagon and Glycerol.

Answer 1

Glucose: Sugar

Glycogen: Carbohydrate - how glucose is stored in animals

Glycerol: Breakdown product of lipids

Glucagon: Hormone that brings super levels back up (it does the opposite of insulin

Question 2

What is the difference between a prokaryote and a eukaryote?

Answer 2

Prokaryotic cells = Bacterial cells:

Much smaller in comparison.

They have cytoplasm and a cell membrane surrounded by a cell wall.

The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids.

Eukaryotic cells = Animal cells and plant cells

Bigger than bacterial / prokaryote cells

Genetic material enclosed in a nucleus

Have a cell membrane and cytoplasm

Question 3

What do animal cells have and what are these sub cellular structures’ functions?

Answer 3

Cytoplasm - Where chemical reactions happen

Nucleus - Contains DNA

Mitochondria - Respiration

Ribosomes - Protein synthesis (making of protein)

Cell membrane - Controls what goes in and out of the cell

Question 4

What do plant cells have that animal cells don’t have?

Answer 4

Chloroplasts containing chlorophyll

Cell wall made of cellulose

Permanent vacuole filled with cell sap

Question 5

What is the cell wall made of?

Answer 5

Cellulose

Question 6

What is the function of chloroplasts?

Answer 6

Photosynthesis - to make glucose

Are able to absorb sunlight energy

Chlorophyll

Question 7

What happens in the growth phase of the cell cycle?

Answer 7

Genetic material is doubled

It increases the number of sub-cellular structures such as ribosomes and mitochondria.

Question 8

What happens once the growth phase is completed?

Answer 8

Mitosis - cell division.

Question 9

Describe the overall process of mitosis.

Answer 9

1. Chromosomes have been duplicated during the growth phase
2. Nuclear membrane breaks down
3. Chromosomes can align along the centre of the cell
4. Sister chromatids are torn apart and pulled to opposite poles of the cell
5. Cytokinesis happens - the cell divides into two cells

Question 10

Describe the products of mitosis?

Answer 10

x2 genetically identical, diploid daughter cells

Question 11

Why is mitosis important?

Answer 11

Growth and repair

Question 12

What is the definition of a stem cell?

Answer 12

A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

Question 13

Where can stem cells be found in humans?

Answer 13

Embryos

Adult bone marrow contains stem cells that can differentiation into blood cells (red or white)

Question 14

Where can stem cells be found in plants?

Answer 14

Meristem - stem cells here can differentiate into any type of plant cell, throughout the life of a plant

Question 15

Why are we interested in stem cells?

Answer 15

Because treatment with stem cells may be able to help conditions such as diabetes (by producing new pancreas cells that can make insulin) and paralysis (by producing new nerve cells).

Question 16

What is therapeutic cloning?

Answer 16

In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment.

Question 17

What are some of the hesitations of using stem cells?

Answer 17

The use of stem cells has potential risks such as transfer of viral infection

Some people have ethical or religious objections.

Question 18

Describe some of the uses of plant stem cells from meristems.

Answer 18

Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.

Rare species can be cloned to protect from extinction.

Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.

Question 19

What is the definition of diffusion?

Answer 19

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

Question 20

What factors affect the rate of diffusion?

Answer 20

Temperature

Concentration gradient

Surface area to volume ratio

(Diffusion distance)

Question 21

Why do multicellular organisms require transport systems but unicellular organisms do not?

Answer 21

A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell, by diffusion, to meet the needs of the organism.

Multicellular organisms have a low surface-area to volume ratio so they require transport systems.

Question 22

Explain how the lungs are adapted for gas exchange.

Answer 22

There are millions of alveoli. The alveoli increase the surface area to volume ratio of the lungs which increases the rate of diffusion.

The wall of the alveoli and the blood capillaries are one cell thick, reducing the diffusion distance

A steep concentration gradient is maintained because the wall of lungs have a very rich blood supply.

Question 23

Explain how the small intestine are adapted for nutrient absorption.

Answer 23

There are millions of villi. The villi increase the surface area to volume ratio.

The wall of the villi are one cell thick, reducing the diffusion distance

A steep concentration gradient is maintained because the small intestines have a very rich blood supply.

Question 24

What is the definition of osmosis?

Answer 24

Water may move across cell membranes via osmosis. Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Question 25

What is the definition of active transport?

Give two examples of uses of active transport.

Answer 25

Active transport moves substances from an area of low concentration to an area of high concentration, against a concentration gradient, using energy from respiration.

Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth.

It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.

Question 26

What is the difference between a cell, a tissue, an organ and an organ system?

Answer 26

Cells are the basic building blocks of all living organisms.

A tissue is a group of identical cells with a similar structure and function.

Organs are aggregations of different tissues performing specific functions.

Organs are organised into organ systems, which work together to form organisms.

Question 27

Where is amylase made?

Answer 27

Salivary glands, mouth

Pancreas

Small intestine

Question 28

Where is lipase made?

Answer 28

Pancreas

Small intestine

Question 29

Where is protease made?

Answer 29

Stomach

Pancreas

Small intestine

Question 30

What does lipase do?

Answer 30

Lipase breaks down lipids into 3x fatty acids and glycerol

Lipid —> Fatty acids x3 + Glycerol

Question 31

What do proteases do?

Answer 31

Proteases break down protein into amino acids

Question 32

What do carbohydrases do?

Answer 32

Carbohydrases break down carbohydrates to simple sugars.

Question 33

What does amylase do?

Answer 33

Amylase is a carbohydrase which breaks down starch.

Question 34

Where are all 3 types of digestive enzymes made?

Answer 34

All 3x are made in the Small intestine and Pancreas

Stomach also makes protease

Mouth also makes amylase

Question 35

What is the role of bile in digestion?

Answer 35

It is alkaline to neutralise hydrochloric acid from the stomach.

It also emulsifies fat: breaks down large lipid droplets into small lipid droplets which increases the surface area:volume ratio. This is to help lipase work faster.

The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.

Question 36

Where is bile made and stored?

Answer 36

Bile is made in the liver and stored in the gall bladder.