Difficult Questions Flashcards
Explain fertilization and Seed formation
A pollen grain germinates to form a pollen tube. the pollen tube grows down to the micropyle of the ovule. A male nucleus passes from the pollen tube into the ovule to fuse with the ovum. This produces a zygote cell. The zygote divides to form the embryo. The embryo consists of the plumule, radicle and cotyledons. The integuments grow and harden into the testa. The ovary grows into the fruit. The other parts of the plant drop off.
Explain Chromosomes and the transfer of genetic information
Chromosomes contain genetic information in the form of genes; chromosomes are passed on in the gametes after cell division. Genes control the characteristics of organisms.
Describe two forms of Natural and Artificial vegetative reproduction
Natural: Runners, vegetative reproduction by runners does not involve a storage organ. A runner is a stem that grows horizontally away from the parent plant. the tip of the runner forms shoots, which grow down into the soil. Shoots also form which become new plants. Nutrients pass from the parent plant to the new plant through the runner until the new plant can produce its own food and become independent after which the runner dies. Examples of plants that produce runners are strawberries and water grass.
Storage organs, the storage organ stores food if growing conditions become unfavourable, the parent plant may die but the storage organ will remain. When the conditions improve, a new plant will grow from this using the stored food. Examples of storage organs include; Bulbs, Corms, and Rhizomes.
Artificial: Cuttings; a part of the plant for example a piece of the stem is removed and placed under suitable conditions. It develops roots and shoots to become a new plant.
Grafting is the insertion of a shoot or bud onto a related plant. The two grow into one plant, which has the advantage of the vigour of a specially chosen root the stock and the quality of the product on the grafted shoot, the scion
Name three sexually transmitted infections, their causes, symptoms and treatments
Syphilis can be contracted by men and women, it is caused by Treponema pallidum a bacterium. symptoms of syphilis are sores on the genitals; incubation period of 2 to 4 weeks. After 8 to 12 weeks, a rash on the body and swollen lymph nodes.
Gonorrhoea can be contracted by men and women; women may show no symptoms. It is caused by Neisseria gonorrhoea a bacterium. Symptoms of gonorrhoea include difficulty passing urine, fever, headache, and discharge from the urethra; the incubation period is about 5 days. infection may spread to other parts of the body. Treatment, gonorrhoea is sensitive to antibiotics, so treatment is effective if caught early.
genital herpes can be contracted by men and women. it is caused by herpes simplex a virus, symptoms include small red painful ulcers on the genitals. There is no cure, but treatment with anti-viral medicine alleviates symptoms.
What is a bimetallic strip and thermostat and how does a bimetallic strip be used to control the temperature of an appliance such as an electric iron
A bimetallic strip is made from two strips of different metals bonded together. Both of the metals expand when they are heated but in different amounts.
A thermostat is used to keep something at a particular temperature. A bimetallic strip can be used in a thermostat.
In an electric iron when the strip is straight, it forms part of an electric circuit. Current flows through the circuit, the heater is on and the iron warms up. if the iron becomes hotter than the required temperature, the strip bends away from the contact, the circuit is broken and the heater is switched off. As the bimetallic strip cools, it straightens again, eventually completing the circuit so current flows and the heater is switched on again.
Define Voltage, Resistance and give the formula for voltage
The energy available to drive the electrons around a circuit is referred to as the voltage. the formula for voltage is V=IR
Resistance is the opposition to current flow in a circuit.
What is the formula for watt, current and the energy transferred by an appliance
W=IV
I=W/V
energy transferred= powertime in hours
KWh= kWh
Define the filament lamp, fluorescent lamp and LED bulbs. compare the type of light emitted, duration, efficiency and cost
refer to book
Explain the chemical digestion of food from the mouth, stomach to the small intestines[duodenum and ileum]
refer to book
What is the word equation and chemical equation of respiration
The word equation of respiration:
Glucose + Oxygen—-;Carbon dioxide + Water + Energy
The chemical equation of respiration:
C6H12O6 + 6O2—;6CO2 + 6H2O + ATP
Explain urine formarion
Pressure filtration occurs in the glomerulus. small molecules, such as glucose, amino acids, hormones, salts, and urea, are forced into the bowman’s capsule. Large molecules, such as blood proteins, remain in the blood.
As the filtrate passes down the proximal convoluted tubule and the loop of Henle, selective reabsorption takes place. Useful substances are reabsorbed from the filtrate into the blood, for example, water, glucose, amino acids and hormones.
The filtrate is now called urine and contains excess water, excess salts and urea; it passes into the collecting ducts and then to the bladder through the ureters, where it is stored.
Explain the peripheral nervous system
The peripheral nervous system consists of bundles of nerve fibres. The individual units of these fibres are called neurones. there are three types of neurons;
The Sensory neuron: These connect with sensory cells, for example, receptors at the tips of the fingers, and conduct impulses from the sensory cells to the central nervous system.
Relay [intermediate] neurones: These act as links between sensory neurones and motor neurones.
Motor neurones: These usually link with muscle cells or glands [effectors] and with relay neurones.
Describe the eye and its parts
refer to the book
What happens to the eye when focusing on distant and near objects
When focusing on distant objects, the ciliary muscles relaxes and the suspensory ligaments are pulled tight. This causes the lens to be thin; the thin lens focuses the light rays on the retina.
When focusing on near objects, the ciliary muscles contracts and the suspensory ligaments slacken. This changes the lens into a bulged shape; this bulged lens then focuses the light rays onto the retina.
Describe the pulmonary circulation
De-oxygenated blood returns from the body and enters the vena cava.
From the vena cava, the blood enters the right atrium and then the right ventricle.
The blood enters the pulmonary artery and goes to the lungs where it becomes oxygenated.
The oxygenated blood returns from the lungs through the pulmonary vein, it enters the left atrium and then the left ventricle.
The blood leaves the left ventricle and enters the aorta.
What does the safety of a blood transfusion depend on
The safety of a transfusion depends on the antigens on the red cells of the donated blood and the antibodies in the plasma of the person receiving the blood.
If the antigen and the antibody match then the transfusion is inappropriate for example donating type A blood to a type B person.
Explain how to treat accidents; Mouth-to-mouth resuscitation electrical shock, burn, and sprains
Mouth-to-mouth resuscitation
1 Place the person on their back and remove anything blocking the mouth.
2 Put one hand on the forehead and the other one under the neck to tilt the head back.
3 Pinch the nostrils with your fingers.
4 Take a deep breath place your lips around the person’s mouth and blow into the lungs until they are filled up.
5 Remove your mouth and wait until the chest falls.
6 Repeat steps 1–5 until the person starts breathing.
Electric shock
If a person is receiving an electrical shock, switch off the current, if the current cannot be switched off, remove the person from the contact by using non-conducting material. Do not touch the person with bare hands instead use gloves.
Burns
Exclude air from the area by covering it with water, clean paper or a clean shirt. Do not apply creams or ointments.
Sprains
1 Wash with cold water.
2 Hold the ankle for example, in its normal position.
3 Wrap a bandage around the joint, above the joint and below the joint several times.
Name three different types of fire extinguishers and explain each
The carbon dioxide fire extinguisher contains carbon dioxide under pressure, it suffocates the fire.
The water fire extinguisher removes the heat and cools the fire.
The chemical fire extinguishers suffocate the fire.
Name three thermometers and their functions
refer to book
Describe the process of water purification
1 filtration; The water first passes through a filtration system to remove large solid particles
2 Sedimentation; The water is passed into a sedimentation tank, where chemicals that cause precipitation of solid particles are added. These particles sink to the bottom of the sedimentation tank.
3 Filtration; The water is passed through a fine filtration process that removes small particles.
4 Chlorination; The water is passed into a container, where chlorine is added to kill bacteria
5 Storage; The purifies water is stored in storage tanks.
State some types of water pollution
Organic waste from untreated sewage increases the amount of bacteria, which use up the dissolved oxygen and hence leads to the death of aquatic organisms.
Oil Spills from oil tankers can be home to some aquatic organisms. They can form slicks on the sea, which prevent oxygen from dissolving and block the sunlight.
Insecticides and Herbicides wash off from the land and can be consumed by aquatic organisms, invading the food chain and becoming toxic to aquatic life.
what are the conditions for the growth of micro-organisms
Micro-organisms need oxygen, water and a suitable temperature to grow. Oxygen is needed for respiration, water for chemical reactions and a temperature of between 25 degrees Celsius and 35 degrees Celsius for optimal enzyme action and cell division.
What are enzymes
Enzymes are catalysts. One enzyme molecule can be used over and over again and so it can break down many food molecules. Enzymes act on molecules called substrates and change them into one or more product molecules.
what are factors that influence enzyme action
Temperature, the optimum temperature for human digestive enzymes is around 37 degrees Celsius. Below the optimum temperature, the enzyme reaction starts to slow down and at very low temperatures it will stop.
pH, enzymes also work best at optimum pH conditions. The pH changes along the alimentary canal. The activity of an enzyme falls either side of its optimum pH value as changes in the pH of the conditions change the 3-dimensional structure of the enzyme to change.
