GCSE Biology Higher Tier Paper 1H Study Notes

Coronary Heart Disease (CHD): Affects the arteries, leading to reduced blood flow to the heart muscle.
Emergency Response:
- Chest compressions put pressure on the heart to manually pump blood around the body.
- Forcing air into the lungs provides oxygen for the blood to transport to tissues.
Treatment and Risk Factors:
- Statins: Drugs used to lower high cholesterol levels in the blood.
- Stents: Mechanical devices inserted into arteries to keep them open and restore blood flow.
- Lifestyle Factors: High dietary salt or fat intake and lack of exercise increase cardiovascular disease (CVD) risk.
- Smoking Data: Increases the risk of various CVDs, with some types showing a percentage increase in risk as high as $70\%$ .

Genetics: CF is an inherited disorder caused by a faulty gene located in the nucleus of a cell.
Systemic Effects: Impacts the lungs, pancreas, and small intestine.
Digestive Impact:
- Thick mucus blocks pancreatic ducts, preventing digestive enzymes from reaching the small intestine.
- Results in difficulty digesting food and poor absorption of nutrients, leading to low body mass.
Gas Exchange (Alveoli):
- Features for efficiency: large surface area, thin walls for short diffusion paths, and an extensive blood supply.
- Reduced Oxygen: CF limits oxygen entry into the blood, reducing the rate of aerobic respiration and decreasing energy availability for the body.

Chemical Tests:
- Benedict's Test: Used to detect sugars (requires a hot water bath; color change from blue to green/yellow/red).
- Iodine Test: Used to detect starch (color change from brown/orange to blue-black).
Digestion in the Mouth: Bread begins to taste sweet because salivary amylase breaks down starch into simple sugars (maltose).
Experimental Variables:
- Independent Variable: The type of bread (e.g., Brown, White, Wholemeal).
- Dependent Variable: Time taken for the bread to taste sweet in seconds.

Leaf Structure:
- Palisade Mesophyll: Contains the most chloroplasts for maximum photosynthesis.
- Spongy Mesophyll: Contains air spaces for gas exchange.
- Meristem: Tissue that retains the ability to differentiate throughout the plant's life.
Vascular Tissues:
- Xylem: Transports water; strengthened by cellulose and lignin.
- Phloem: Transports dissolved sugars via translocation.
- Companion Cells: Contain many mitochondria to provide energy for the active transport of sugars into phloem cells.

Antibiotics: Drugs like penicillin kill bacteria but are ineffective against viruses.
Antibiotic Resistance: Evidence of resistance is shown when bacteria growth is not inhibited around an antibiotic disc (no zone of inhibition).
Viruses:
- Cannot be grown on agar because they require a host cell to replicate.
- Difficult to develop drugs for because viruses live and replicate inside human cells.
- AIDS: Caused by a virus that specifically damages white blood cells.

Experimental Factors:
- Photosynthesis requires light (blocked by black paper), carbon dioxide, and chlorophyll (absent in white parts of variegated leaves).
- Starch presence is the primary indicator that photosynthesis has occurred (detected by iodine).
Limiting Factors: Light intensity, carbon dioxide concentration, and temperature.
Measurement: Rate can be measured by the volume of oxygen produced over time.
Inverse Square Law:
- $\text{light intensity} \propto \frac{1}{\text{distance}^2}$

Cell Cycle: Before division, DNA replicates and the quantity of sub-cellular structures (e.g., ribosomes, mitochondria) increases.
Cancer: Defined as uncontrolled cell division resulting from genetic changes.
Magnification Calculation:
- $\text{Length} = \frac{\text{Volume}}{\pi \times \text{radius}^2}$
- $\text{Magnification} = \frac{\text{Image Size}}{\text{Real Size}}$
Drug Treatments: Some drugs (like Drug X) treat cancer by preventing the attachment of fibers to chromosomes, stopping cell division.
Drug Testing: Preclinical testing involves testing drugs on live tissues or chemicals in a laboratory before human clinical trials.