Edexcel Biology Unit 5 Q&A
Unit 5
Describe the two process by which hormones can cause certain genes to be turned on. (4)
Any 2 from:
- A hormone binds to a receptor in the cell surface membrane
- Idea of the receptor causing (chemical) changes inside the cell
- A (functional) {second messenger} activates an {enzyme/transcription factor/eq}
Any 2 from:
- Idea of a hormone entering the cell through the cell membrane
- The hormone binds to a receptor
- The {hormone-receptor complex/eq} acts as a transcription factor
What is the negative feedback principle? (2)
- Idea of responding to deviations from normal levels by reversing their effect
- Idea of helping to maintain normal levels
- Any correct example (cools the body down when temperature rises/Increases blood pressure when it drops/eq)
Describe the ATP/PC system. (3)
- Idea of {ADP} concentration rising
- Causes {phosphocreatine/creatine phosphate} to break down into creatine and an (inorganic) phosphate
- The (inorganic) phosphate reacts with the ADP to synthesise ATP
- Credit any one correct equation (PCr ----> Cr + Pi/ADP + Pi ----> ATP/eq)
- Idea of {phosphocreatine/creatine phosphate} regenerating when ADP levels drop
Article related
Give one reason why it is expected that long-lived animals are likely to develop cancer, as opposed to shorter-lived animals. [Paragraph 21] (1)
- Idea of more cell division/mitosis occurring leading to a higher accumulation of mutations that could lead to cancer
Researchers are looking at "the similarities and differences of how varied but closely related species deal with cancer." [Paragraph 18]
*Explain how one species can become two different closely related species. (6)
Award one mark for answers written in a logical order and terms in italics must be spelled correctly
- Idea of one population expanding and becoming two
- Reference to a {restriction in gene flow/eq}
- Correct example of how gene flow is restricted (e.g. geographical features)
- Each
Describe the two process by which hormones can cause certain genes to be turned on. (4)
Any 2 from:
- A hormone binds to a receptor in the cell surface membrane
- Idea of the receptor causing (chemical) changes inside the cell
- A (functional) {second messenger} activates an {enzyme/transcription factor/eq}
Any 2 from:
- Idea of a hormone entering the cell through the cell membrane
- The hormone binds to a receptor
- The {hormone-receptor complex/eq} acts as a transcription factor
What is the negative feedback principle? (2)
- Idea of responding to deviations from normal levels by reversing their effect
- Idea of helping to maintain normal levels
- Any correct example (cools the body down when temperature rises/Increases blood pressure when it drops/eq)
Describe the ATP/PC system. (3)
- Idea of {ADP} concentration rising
- Causes {phosphocreatine/creatine phosphate} to break down into creatine and an (inorganic) phosphate
- The (inorganic) phosphate reacts with the ADP to synthesise ATP
- Credit any one correct equation (PCr ----> Cr + Pi/ADP + Pi ----> ATP/eq)
- Idea of {phosphocreatine/creatine phosphate} regenerating when ADP levels drop
Article related
Give one reason why it is expected that long-lived animals are likely to develop cancer, as opposed to shorter-lived animals. [Paragraph 21] (1)
- Idea of more cell division/mitosis occurring leading to a higher accumulation of mutations that could lead to cancer
Researchers are looking at "the similarities and differences of how varied but closely related species deal with cancer." [Paragraph 18]
*Explain how one species can become two different closely related species. (6)
Award one mark for answers written in a logical order and terms in italics must be spelled correctly
- Idea of one population expanding and becoming two
- Reference to a {restriction in gene flow/eq}
- Correct example of how gene flow is restricted (e.g. geographical features)
- Each