Biology

Question 1

How to work out magnification

Answer 1

Image size
———————— = magnification
Size of real object

Question 2

What is a gene

Answer 2

Each sections of a chromosomes that codes for a particular protein

Question 3

How many chromosomes does each human body cell contain

Answer 3

46 chromosomes. Arranged in 23 pairs. The 23 pair are the sex

Question 4

What are the male and female chromosome pairs

Answer 4

Male - XY
Female - XX

Question 5

What are the three stages of the cell cycle (mitosis)

Answer 5

Stage 1 - Replication of DNA and organelles

Stage 2 (Mitosis) - The chromosomes move apart and the nucleus divides. Genetic material then splits into 2

Stage 3 - The cytoplasm divides into two and the new cell membrane separates off to give two new genetically identical daughter cells

Question 6

Structure and function of the meristem cell

Answer 6

Structure:
-undifferentiated cells
-Contains many ribosomes

Function:
-found in zones where plant growth takes place. (Shoots and Roots)
-can differentiate to produce all types of plant cells

Question 7

Embryonic stem cells vs adult stem cells

Answer 7

Adult stem cells - only produce a few types of specialised cell. For growth or to replace old or damaged cells

Embryonic stem cells - can differentiate into any specialised cells

Question 8

What is diffusion

Answer 8

-Movements of particles from a high to low concentration
- This usually results in equilibrium (same number of particles on each side)
- particles move down the concentration gradient

Question 9

What factors affect diffusion

Answer 9

Concentration - The greater the difference in concentration the quicker the rate of diffusion

Temperature - The higher the temperature, the more kinetic energy the particles will have, so the will move and mix more quickly

The surface area - The greater the surface area, the after the rate of diffusion

Question 10

What is osmosis

Answer 10

Osmosis is the diffusion of water molecules from a low concentration solution to a high concentration solution, across a partially permeable membrane

Question 11

What happens during osmosis

Answer 11

During osmosis, water molecules diffuse from pure water or dilute solution (high concentration) to more concentrated solutions (low concentration)

Question 12

Osmosis and animal cells

Answer 12

In dilute solutions osmosis can cause animal cells to swell up and burst

In concentrated solutions water loss causes the sell’s to shrink resulting in them not being able to transport oxygen effectively

Question 13

Active transport

Answer 13

Active transport is the process by which dissolved molecules move across a cell membrane from a lower to a higher concentration

Question 14

What happens in active transport

Answer 14

Particles move against the concentration gradient and therefore require an input of energy from the cell

Question 15

How are specialised cells made

Answer 15

Specialised cells are made through a process called differentiation

Question 16

What are examples of specialised cells

Answer 16

Palisade cells- contains chloroplast

white blood cells- contain enzymes to destroy pathogens

red blood cells-contain haemoglobin to bind oxygen

Root hair cell- has a root hair to increase the surface area for water and mineral absorption

Sperm cell- has many mitochondria to produce energy for respiration

Question 17

What are examples of tissues

Answer 17

-Muscle
-lining of intestine
-lining of lungs
-phloem (tubes that carry dissolved sugar around a plant)
-root hair tissue

Question 18

What are examples of organ systems

Answer 18

Circulatory system
respiratory system
Digestive system
Nervous system
Leaf canopy

Question 19

What is digestion

Answer 19

Digestion is were relatively large insoluble molecules are broken down into smalle soluble molecules so they can be absorbed into the blood stream and delivered to cells in the body

Question 20

How is digestion absorption fastened

Answer 20

The surface of the small intestine is folded, and has cells called villi and micro villi which increases the surface area of the cell which increases the rate of absorption

Question 21

What is bile

Answer 21

-It neutralises stomach acid and produces the optimum ph for pancreatic enzymes

-It is produced in the liver and is stored in the Gail bladder

Question 22

What are catalysts and substrates

Answer 22

Catalysts- increase rate of reaction ls without being used up

Substrate- substances that enzymes work on

Question 23

What is the lock and key theory

Answer 23

-Shape of enzymes active site is complimentary to the shape of a particular substrate

-they then bind together and
the reaction then takes place rapidly

-the products are released from the active site

Question 24

What is denaturing

Answer 24

Enzymes only work at a temperature below 60•c, increasing the temperature to 60•c will cause permanent change to the shape of the active site (denatured)

Question 25

How are protein molecules formed

Answer 25

By a long chain of amino acids

Question 26

How are starch molecules formed

Answer 26

By a long chain of gluclose