Key Concepts in Biology - 1

Question 1

What are the two main types of cells?

Answer 1

Cells can be either eukaryotic or prokaryotic.

Question 2

What are eukaryotic cells?

Answer 2

Eukaryotic cells are complex and include all animal and plant cells.

Question 3

What are prokaryotic cells?

Answer 3

Prokaryotic cells are smaller and simpler, e.g. bacteria.

Question 4

What are eukaryotes?

Answer 4

Eukaryotes are organisms that are made up of eukaryotic cells.

Question 5

What is a prokaryote?

Answer 5

A prokaryote is a prokaryotic cell (it’s a single-celled organism).

Question 6

What are subcellular structures?

Answer 6

The different parts of a cell are called subcellular structures.

Question 7

What is the function of the nucleus in animal cells?

Answer 7

The nucleus contains genetic material that controls the activities of the cell.

Question 8

What is the cytoplasm?

Answer 8

The cytoplasm is a gel-like substance where most of the chemical reactions happen.

Question 9

What is the role of the cell membrane?

Answer 9

The cell membrane holds the cell together and controls what goes in and out.

Question 10

What happens in the mitochondria?

Answer 10

Most of the reactions for respiration take place in the mitochondria.

Question 11

What do ribosomes do?

Answer 11

Ribosomes are involved in the translation of genetic material in the synthesis of proteins.

Question 12

What extra structures do plant cells have compared to animal cells?

Answer 12

Plant cells usually have a rigid cell wall, a large vacuole, and chloroplasts.

Question 13

What is the function of the rigid cell wall?

Answer 13

The rigid cell wall, made of cellulose, supports and strengthens the cell.

Question 14

What is the purpose of the large vacuole in plant cells?

Answer 14

The large vacuole contains cell sap and maintains internal pressure to support the cell.

Question 15

What do chloroplasts do?

Answer 15

Chloroplasts are where photosynthesis occurs, making food for the plant.

Question 16

What is unique about bacterial cells?

Answer 16

Bacterial cells are smaller than plant or animal cells and have no nucleus.

Question 17

What is chromosomal DNA in bacterial cells?

Answer 17

Chromosomal DNA is one long circular chromosome that controls the cell’s activities.

Question 18

What are plasmids?

Answer 18

Plasmids are small loops of extra DNA that aren’t part of the chromosome.

Question 19

What is the function of the flagellum in bacterial cells?

Answer 19

The flagellum is a long, hair-like structure that helps the bacterium move.

Question 20

What are specialised cells?

Answer 20

Specialised cells have a structure adapted to their function.

Question 21

Are specialised cells unicellular?

Answer 21

No, their Multicellular

Question 22

What is the role of egg cells in reproduction?

Answer 22

Egg cells carry female DNA and nourish the developing embryo.

Question 23

How is the egg adapted?

Answer 23

1. it contains nIt contains nutrients in the cytoplasm to feed the embryo.

It has a haploid nucleus.

Straight after fertilisation, its membrane changes structure to stop any more sperm getting in. This makes sure the offspring end up with the right amount of DNA.

trients in the cyt

Question 24

What is the function of sperm cells?

Answer 24

Sperm cells transport the male’s DNA to the female’s egg.

Question 25

How is a sperm adapted?

Answer 25

1.A sperm cell has a long tail so it can swim to the egg. 2.It has lots of mitochondria in the middle section to provide the energy (from respiration) needed to swim this distance. 3.It also has an acrosome at the front of the 'head', where it stores enzymes needed to digest its way through the membrane of the egg cell. 4.It also contains a haploid nucleus.

Question 26

What do ciliated epithelial cells do?

Answer 26

Ciliated epithelial cells move substances along the surface of tissues.

Question 27

What is the purpose of microscopes?

Answer 27

Microscopes are used to magnify images and increase resolution.

Question 28

What is the difference between light and electron microscopes?

Answer 28

Light microscopes use light and can view living cells, while electron microscopes use electrons and have higher magnification and resolution.

Question 29

How do you prepare a specimen for viewing under a light microscope?

Answer 29

Take a thin slice, place it on a slide with water, add stain if necessary, and cover with a cover slip.

Question 30

What is the formula for total magnification?

Answer 30

Total magnification = eyepiece lens magnification × objective lens magnification.

Question 31

How do you calculate magnification using image size and real size?

Answer 31

Magnification = image size / real size.

Question 32

What is standard form?

Answer 32

Standard form is a way to express very big or small numbers more manageably.

Question 33

What is the role of enzymes?

Answer 33

Enzymes are catalysts produced by living things to speed up chemical reactions.

Question 34

What is the 'lock and key' mechanism?

Answer 34

The substrate fits into the enzyme's active site like a key fits into a lock.

Question 35

How does temperature affect enzyme activity?

Answer 35

Higher temperatures increase reaction rates until the enzyme denatures.

Question 36

What is denaturation?

Answer 36

Denaturation occurs when an enzyme's active site changes shape, preventing substrate binding.

Question 37

What factors affect enzyme activity?

Answer 37

Temperature, pH, and substrate concentration affect the rate of enzyme-catalysed reactions.

Question 38

What is the optimum temperature for enzymes?

Answer 38

All enzymes have an optimum temperature that they work best at.

Question 39

What is the optimum pH for most enzymes?

Answer 39

All enzymes have an optimum pH that they work best at, often around neutral pH 7, but not always.

Question 40

What is an example of an enzyme with a specific optimum pH?

Answer 40

Pepsin is an enzyme that works best at pH 2, suitable for the acidic conditions in the stomach.

Question 41

How does substrate concentration affect enzyme activity?

Answer 41

The higher the substrate concentration, the faster the reaction, as it increases the likelihood of enzyme-substrate interactions.

Question 42

What happens when substrate concentration is too high?

Answer 42

After a certain point, all active sites of the enzymes are full, and adding more substrate makes no difference.

Question 43

What is the purpose of the iodine solution in the amylase experiment?

Answer 43

Iodine solution is used to detect starch; it changes from browny-orange to blue-black in the presence of starch.

Question 44

What is the first step in investigating the effect of pH on amylase activity?

Answer 44

Put a drop of iodine solution into every well of a spotting tile.

Question 45

What temperature should the water be heated to in the amylase experiment?

Answer 45

Heat the water to 35 °C.

Question 46

How do you calculate the rate of reaction?

Answer 46

Rate = 1000 / time.

Question 47

What was the rate of reaction for amylase at pH 6 if it took 50 seconds?

Answer 47

What was the rate of reaction for amylase at pH 6 if it took 50 seconds?

Question 48

What do enzymes do to big molecules?

Answer 48

Enzymes break down big molecules into smaller ones for growth and other life processes.

Question 49

What are carbohydrases?

Answer 49

Enzymes that convert carbohydrates into simple sugars, e.g., amylase breaks down starch.

Question 50

What do proteases do?

Answer 50

Proteases convert proteins into amino acids.

Question 51

What do lipases do?

Answer 51

Lipases convert lipids into glycerol and fatty acids.

Question 52

What is diffusion?

Answer 52

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.

Question 53

What is osmosis?

Answer 53

Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.

Question 54

What is active transport?

Answer 54

Active transport is the movement of particles across a membrane against a concentration gradient using energy.

Question 55

What is the first step in investigating osmosis with potato cylinders?

Answer 55

Prepare sucrose solutions of different concentrations ranging from pure water to a very concentrated sucrose solution.

Question 56

How do you measure the percentage change in mass in the osmosis experiment?

Answer 56

Percentage change = (final mass - initial mass) / initial mass × 100.