Intro into AS (transition)

Question 1

Prokaryotes

Answer 1

single celled organisms (bacteria), they have:
- no nucleus with circular DNA free in the cytoplasm
- cell wall made from peptidoglycan
- no membrane bound organelles
- small ribosomes

Question 2

Eukaryotes (animal cells)

Answer 2

• linear DNA contained inside a nucleus
• no cell wall
• larger ribosomes and many membrane-bound organelles

Question 3

Eukaryotes (plant cells)

Answer 3

• a cell wall
• a large vacuole containing cell sap
• chloroplasts

Question 4

facilitated diffusion

Answer 4

• Large molecules cannot diffuse across cell membranes by themselves. They must be helped by carrier proteins.
• Each molecule has its own carrier protein that allows the molecule through the cell membrane without the need for energy

Question 5

active transport requirements

Answer 5

• a carrier protein
• energy (ATP)
• against a concentration gradient

Question 6

hydrogen bonds (in DNA)

Answer 6

Each base in a DNA strand links to a base on the opposite strand in the helix to form cross-links of hydrogen bonds

Question 7

gene

Answer 7

a sequence of DNA which codes for a protein

Question 8

A (DNA)

Answer 8

Adenine

Question 9

T (DNA)

Answer 9

Thymine

Question 10

G (DNA)

Answer 10

Guanine

Question 11

C (DNA)

Answer 11

Cytosine

Question 12

The two processes in protein synthesis

Answer 12

• transcription (takes place in the nucleus)
• translation (takes place at the ribosomes)

Question 13

Protein synthesis process

Answer 13

1. A complementary mRNA strand is made using the DNA as a template
2. The mRNA leaves the nucleus and attaches to the ribosome in the cytoplasm
3. A triplet of bases on the mRNA (codon) code for specific amino acids
4. The amino acids are delivered to the ribosome by tRNA
5. Peptide bonds are formed between the amino acid to make the polypeptide

Question 14

Atrioventricular valves (between atrium and ventricles)

Answer 14

• open to allow blood to flow from the atrium into the ventricles
• close when the pressure in the ventricles rises to prevent backflow

Question 15

Semilunar valves (in the aorta and pumonary artery)

Answer 15

• open to allow blood from the ventricles to flow into the arteries
• close to prevent backflow into the ventricles as the heart relaxes

Question 16

How is the low oxygen concentration maintained in the blood near the alveolus?

Answer 16

the blood is moving and carrying oxygen away

Question 17

pulmonary system

Answer 17

pumps blood around the lungs

Question 18

systemic system

Answer 18

pumps blood around the rest of the body

Question 19

taxonomy

Answer 19

• science of desribing, classifying and naming living organisms
• aim is to group organisms to accurately identify them and represent their ancestral relationships

Question 20

why is classification important?

Answer 20

• make sure international biologists are referring to same one when discussing
• to monitor changes in populations of different types of organisms
• to know how different types of living organisms are related to eachother

Question 21

morphology

Answer 21

the study of the external features (size, shape and structure) and the relationships in the structures of a particular organism or among organisms

Question 22

anatomy

Answer 22

deals with the study of shape, structure, and internal features of an organism

Question 23

linnaean system

Answer 23

a system of classifying all organisms into groups according to similarities in their characteristics

Question 24

more accurate means of classification

Answer 24

the sequence of bases in DNA and of amino acids in proteins