Biology 2b Summary Questions

Question 1

What is the definition of a catalyst?

Answer 1

A substance which speeds up the rate of reaction without being changed or used up in the reaction.

Question 2

Why does an enzyme-catalysed reaction stop when the reaction mixture is heated above a certain temperature?

Answer 2

The enzyme becomes denatured so they reaction stops as it doesn’t work properly. The enzyme bonds break, so they loose their shape that means they catalyse a certain reaction.

Question 3

Which three places in the body produces amylase?

Answer 3

Salivary glands, pancreas and small intestine.

Question 4

Where in the body is bile:

a) produced
b) stored
c) used

Answer 4

a) liver
b) gall bladder
c) stomach

Question 5

Why does the stomach produce hydrochloric acid?

Answer 5

So that the stomach has the right pH for the enzyme protease to work (very acidic).

Question 6

What is the word equation for aerobic respiration?

Answer 6

Glucose + Oxygen —> Carbon dioxide + Water

Question 7

What is anaerobic respiration and what is the word equation?

Answer 7

Respiration that takes place without oxygen.

Glucose —> Carbon dioxide + Lactic acid

Question 8

How does DNA control the activities in the cell?

Answer 8

Genes code how amino acids are strung together to make different proteins, and DNA also determines what proteins the cell produce, therefore what type of cell it is.

Question 9

What is differentiation in a cell?

Answer 9

The process in which a cell changes to become specialised for its job.

Question 10

Which chromosome in the human body causes male characteristics?

Answer 10

The Y chromosome causes male characteristics.

Question 11

What is an allele?

Answer 11

A different form of a gene that causes different characteristics e.g. blonde or brown hair.

Question 12

What does;
a) homozygous
b) heterozygous
mean?

Answer 12

a) both alleles are the same e.g. BB or bb

b) alleles are different e.g. Bb

Question 13

Describe the basic difference between a recessive allele and a dominant one.

Answer 13

Two recessive alleles have to be in place for the characteristic to be shown. As soon as a dominant allele is shown, then the person will get that characteristic, e.g. blonde hair (b) is recessive so to have blonde hair you need bb alleles.

Question 14

If both parents carry a recessive allele for cystic fibrosis, what is the probability of their child being a carrier?

Answer 14

25%.

Question 15

What is polydactyly?

Answer 15

Being born with extra fingers or toes.

Question 16

Describe the three ways a fossil can form and give examples of each.

Answer 16

1) gradual replacement - teeth, bones etc that don’t decay easily, eventually get replaced by minerals forming a rock-like substance so the fossil stays distinct
2) casts and impressions - if a footprint is in soft clay, the clay will harden around the imprint leaving an impression of the footprint
3) preservation - in amber and tar pits there is no oxygen or moisture so decay microbes can’t survive, glaciers are too cold for decay microbes to work, peat bogs are too acidic for decay microbes

Question 17

What are three reasons why some species become extinct?

Answer 17

1) rapid environmental change
2) new predators
3) new diseases
4) can’t compete with another (new) species for food
5) catastrophic event eg volcanic eruption
6) new species (speciation)

Question 18

What is speciation? Explain how geographical isolation can lead to speciation.

Answer 18

Speciation is the development of a new species. it occurs when populations of the same species become so different that they can no longer beed together to produce fertile offspring.

1) two populations of the same species
2) physical barriers separate populations
3) populations adapt to new environments
4) development of a new species