Biology: Cells, Genetics, and Life

• There are 40 questions in the paper
• The total mark for the paper is 40
• Each correct answer will score one mark

Characteristics of Living Organisms

• Sensitivity is exemplified by a person rapidly moving their hand away from a hot object

Genetic Modification

• Bacteria are used in genetic modification as they have plasmids

Cell Structures

• Cytoplasm, cell membrane, cell wall, and chloroplast are structures contained in cells
• Cytoplasm and cell membrane are found in all living organisms

Cell Magnification

• A student draws a red blood cell with a diameter of 20 mm
• The actual diameter is 0.008 mm
• The magnification of the student's drawing is ×2500

Plant Cells in Solutions

• Plant cells are immersed in distilled water, low concentration sucrose solution, and high concentration sucrose solution
• Low concentration sucrose solution has a higher water potential than the plant cell cytoplasm
• High concentration sucrose solution has a lower water potential than the plant cell cytoplasm
• In distilled water cells are turgid
• In a low concentration sucrose solution cells are plasmolysed
• In a high concentration sucrose solution cells are flaccid

Energy and Respiration

• Active transport requires energy from respiration

Restriction Enzymes

• Restriction enzymes cut the sticky end of the DNA of a plasmid
• The correct sequence of the missing bases is CAGTG

Food Tests

• Iodine solution is used to test for a food substance and a positive result is indicated by a colour change to blue-black

Lipase Investigation

• Lipase breaks down fats in milk
• The contents will become acidic most quickly in the test-tube containing milk, bile and lipase

Photosynthesis Experiment

• The rate of photosynthesis in an aquatic plant is measured by the rate of bubble release
• As light intensity increases, the rate of bubble release increases and then becomes constant
• The rate of bubble release becomes constant at high light intensities when light intensity becomes a limiting factor

Photosynthesis Location

• Photosynthesis takes place in the leaf of a flowering plant in structures 1 & 4.

Bile Storage

• The gall bladder stores bile in the alimentary canal and associated organs

Villi Function

• Villi increase the efficiency of the absorption of nutrients and provide a large surface area in humans

Carbohydrate Molecules

• Carbohydrate molecules broken down through the alimentary canal are represented correctly in row D

Digestive Enzymes

• Lipase acts in acidic conditions, maltase acts in the stomach and trypsin is secreted by the pancreas

Diet and Constipation

• Fibre in a healthy diet helps to prevent constipation

Transpiration Rate

• The transpiration rate of a well-watered plant is highest on a hot, dry, windy day

Sucrose and Photosynthesis

• The leaves are a source of sucrose and the fruits are a sink during photosynthesis in a flowering plant

Double Circulatory System

• An advantage of having a double circulatory system is that deoxygenated and oxygenated blood are separated to allow a high rate of oxygen supply to the tissues

Coronary Heart Disease

• Part A is blocked in coronary heart disease in the external structure of the human heart

Cholera and Diarrhoea

• Cholera toxins cause diarrhoea by secreting chloride ions out of the small intestine lowering the water potential

Immunity

• Passive immunity is developed by babies from the antibodies they receive in breast milk

Gas Exchange System

• The diaphragm contracts to cause breathing in and the cilia carry mucus to the throat

Oxygen Debt

• Aerobic respiration of lactic acid in the liver removes the oxygen debt caused by vigorous exercise

Kidney Function

• Glucose is completely reabsorbed into the blood from the kidney nephrons in healthy people

Pupil Size and Lens Shape

• In a brightly lit room when reading a mobile phone text message the pupil size is small and the lens shape is fat

Body Temperature Regulation

• Vasodilation increases blood flow to the skin surface capillaries and maintains a constant internal temperature on a hot day

Blood Glucose Concentration

• An increased release of insulin leads to a decrease in blood glucose concentration

Antibiotics

• Antibiotics kill bacteria but do not affect viruses

Flower Structure

• Structure X is the pollen tube within the carpel of a flower after pollination

Low Fertility

• Causes of low fertility in person P is too many sperm cannot digest jelly coat of egg cell
• Causes of low fertility in person Q is too many sperm cannot move to oviduct

Stem Cells

• Stem cells are described as unspecialised

Menstrual Cycle Hormones

• Hormone B represents progesterone during the menstrual cycle

Genetic Disorders

• The pedigree diagram that proves a genetic disorder must be caused by a dominant allele is A

Meiosis Statements

• Meiosis does not produce genetically identical cells and is not involved in repair of damaged tissues

Natural Selection

• Leafy sea-dragons that looked like seaweed were better adapted to their environment and survived passed on the allele for their appearance to their offspring

Biological Systems

• The Sun is the main source of energy input to biological systems

Nitrate Removal

• Denitrifying bacteria and plants remove nitrate ions from soil

Endangered Organisms

• Habitat destruction and polution are two reasons for organisms becoming endangered

Genetic Modification in Agriculture

• Inserting genes into crop plants to improve the nutritional qualities of the plant is an example of the use of genetic modification in agriculture