y9 content

Question 1

What are the small basic units of fats/lipids, proteins, glucose and starch?

Answer 1

fats/lipids –> 3 fatty acids and one glycerol

proteins –> amino acids

glucose –> N/A

starch –> glucose

Question 2

What are the testing methods for fats/lipids, proteins, glucose and starch?

Answer 2

fats/lipids –> add ethanol then water
positive result: clear to white emulsion

proteins –> biurets solution
positive result: blue to purple

glucose –> benedict’s solution (+heat)
positive result: blue to brick red

starch –> iodine solution
positive result: orange to blue/black

Question 3

What are the key differences between starch and glucose?

Answer 3

Glucose is a soluble monosaccharide (one sugar)

Starch is an insoluble polysaccharide (many sugars)

Single molecule of glucose: C6H12O6
Starch is long chains of this molecule.

Question 4

What role does amylase play in digestion?

Answer 4

Amylase is found in our saliva and breaks down starch into maltose.

Question 5

What role do the teeth play in digestion?

Answer 5

Teeth break down food, increasing surface area for enzymes to work.

Question 6

What is the name of the process of squeezing bolus down the oesophagus and how does it work?

Answer 6

Peristalsis squeezes the bolus down into the stomach. Peristalsis is the involuntary contraction and relaxation of longitudinal and circular muscles throughout the digestive tract.

Question 7

How does the stomach physically digest food?

Answer 7

Food is churned in the stomach, further breaking it down and increasing its surface area for enzymes to work.

Question 8

How does the stomach chemically digest food?

Answer 8

Hydrochloric acid in the stomach kills pathogens in the food.

Pepsin (a protease) breaks down protein into amino acids

Low optimum pH for enzyme function

Question 9

How does the duodenem contribute to digestion?

Answer 9

Gall bladder releases bile which emulsifies lipids (large surface area) and neutralises the acids.

Pancreas releases enzymes (tripsin, lipase, amylase) in the pancreatic juice

Question 10

How does the illum contribute to digestion?

Answer 10

The illum has a big surface area, short diffusion distance and high concentration gradient.

Nutrients absorb into the bloodstream and then assimilates out.

Question 11

What happens in the large intestine?

Answer 11

Excess water is removed.

Question 12

What is egestion?

Answer 12

Faeces leaves the rectum through the anus.

Question 13

What is MRS C GREN?

Answer 13

Movement: can change position
Reproduction: can have offspring either sexually or asexually
Sensitivity: can detect stimuli, such as light, and respond to them

Control: can control their internal environment (homeostasis)

Growth: can increase mass
Respiration: can produce energy either aerobically or anaerobically
Excretion: can remove waste substances of metabolic reactions
Nutrition: can absorb nutrients in order to use them for growth and repair

Question 14

What is a eukaryote?

Answer 14

Eukaryotes are organisms that have a nucleus and organelles that are found within a plasma membrane.

Question 15

What is the function of the nucleus?

Answer 15

• contains genetic material, the DNA which codes for a particular protein
• enclosed in a nuclear membrane

Question 16

What is the function of the cytoplasm?

Answer 16

• liquid substance in which chemical reactions occur
• contains enzymes
• organelles are found in it

Question 17

What is the function of the cell membrane?

Answer 17

• contain receptor molecules to identify external signals
• selectively controls what enters and leaves the cell

Question 18

What is the function of the mitochondria?

Answer 18

• where aerobic respiration reactions occur, providing energy for the cell

Question 19

What is the function of the ribosomes?

Answer 19

• where protein synthesis occurs
• found on a structure called the rough endoplasmic reticulum

Question 20

What are the four different types of eukaryote?

Answer 20

Plants, animals, fungi, protoctists

Multicellular: plants, animals, fungi
Unicellular: protoctists, fungi

Question 21

What is a prokaryote?

Answer 21

Prokaryotes do not have a nucleus or membrane-bound organelles.

Question 22

What is a pathogen?

Answer 22

Pathogens are disease-causing organisms and can be fungi, bacteria, protoctists or viruses.

Question 23

What are the four different types of pathogen?

Answer 23

Virus, bacteria, fungi, protists

Question 24

What is a specialised cell?

Answer 24

Specialised cells are those which have developed certain characteristics in order to perform particular functions.

Question 25

What is differentiation?

Answer 25

Cells specialise by undergoing differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role.

Question 26

How and why are sperm cells specialised?

Answer 26

Sperm cells are specialised to carry the male’s DNA to the egg cell (ovum) for successful reproduction.

• streamlines head and long tail to aid swimming
• many mitochondria which supply the energy to allow the cell to move
• the top of the head (acrosome) has digestive enzymes which break down the outer layers of membrane of the egg cell

Question 27

How and why are nerve cells specialised?

Answer 27

Nerve cells are specialised to transmit electrical impulses quickly from one place in the body to another.

• the axon is long, enabling the impulses to be carried along long distances
• having lots of extensions from the cell body (dendrites) means branched connections can form with other nerve cells
• the nerve endings have many mitochondria which supply the energy to make special transmitter chemicals called neurotransmitters. These allow the impulse to be passed from one cell to another

Question 28

How and why are muscle cells specialised?

Answer 28

Muscle cells are specialised to contract quickly to move bones or simply to squeeze, therefore causing movement.

• special proteins slide over each other, causing the muscle to contract
• lots of mitochondria to provide energy from respiration for contraction
• they can store glycogen that is used in respiration by mitochondria

Question 29

How and why are root hair cells specialised?

Answer 29

Root hair cells are specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots.

• have a large surface area due to root hairs, meaning more water can move in as rate of osmosis is increased
• the large permanent vacuole affects the speed of movement of water from soil to cell
• mitochondria to provide energy from respiration for the active transport of mineral ions into the root hair cell

Question 30

How and why are xylem cells specialised?

Answer 30

Xylem cells are specialised to transport water and mineral ions up the plant from the roots to the shoots.

• upon formation, lignin is deposited, causing cells to die. They become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
• lignin is deposited in spirals which helps the cells withstand the pressure from movement of water

Question 31

How and why are phloem cells specialised?

Answer 31

Phloem cells are specialised to carry the products of photosynthesis (food) to all parts of the plant.

• cell walls form structures called sieve plates when they break down, allowing the movement of substances from cell to cell
• despite losing many sub-cellular structures, the energy these cells need to be alive is supplied by the mitochondria of the companion cells

Question 32

What is a stem cell?

Answer 32

A stem cell is an undifferentiated cell which can undergo division to produce many
more similar cells. These are important in development, growth and repair.

Question 33

What are the three types of stem cell?

Answer 33

Embryonic stem cell:
- Form when an egg and sperm cell fuse to form a zygote
- They can differentiate into any type of cell in the body

Adult stem cell:
- If found in bone marrow they can form many types of cells (not any type, like
embryonic stem cells can) including blood cells

Meristems (in plants):
- found in root and shoot tips
- They can differentiate into any type of plant, and have this ability throughout the
life of the plant

Question 34

What are some risks and benefits that come with using stem cells in medicine?

Answer 34

Pros:
- Can be used to replace damaged cells, such as in type 1 diabetes, multiple sclerosis and paralysis caused by spinal cord injuries
- Bone marrow transplants for adult stem cells can be used to treat blood cell cancers, such as leukaemia
- Can grow whole organs for transplants
- No rejection, if it is made from the patient’s
own cells
- Can allow for the testing of millions of
potential drugs without animal testing

Cons:
- Ethical issues of destroying unused embryos
- No guarantee in how successful these
therapies will be and if there will be any long
term effects
- Mutations could occur in cultured stem cells
- Difficult to find suitable stem cell donors

Question 35

What is the function of carbohydrates in humans?

Answer 35

A high energy source.

Question 36

What is the function of proteins in humans?

Answer 36

For growth and repair

Question 37

What is the function of lipids in humans?

Answer 37

1. High energy source
2. Insulation

Question 38

What is the function of dietary fibre in humans?

Answer 38

To provide roughage to keep food moving through gut

Question 39

What is the function of Vitamin A in humans?

Answer 39

1. Improved vision, especially in the dark
2. Growth

Question 40

What is the function of Vitamin C in humans?

Answer 40

Helps with absorption of iron

Question 41

What is the function of Vitamin D in humans?

Answer 41

Helps with absorption of calcium

Question 42

What is the function of calcium in humans?

Answer 42

Helps bone and teeth strength

Question 43

What is the function of iron in humans?

Answer 43

Needed for haemoglobin - deficiency can
cause anaemia

Question 44

What is the function of water in humans?

Answer 44

Needed for cell reactions to take place