Genetics
What is an allele?
An alternative form of a gene
which blood component transports oxygen in the blood?
Red blood cells have heamoglobin, the molecule that carries O2
Which sequence correctly describes a simple reflex arc:
A. Effector → sensory neurone → relay neurone → motor neurone → receptor
B. Receptor → motor neurone → relay neurone → sensory neurone → effector
C. Receptor → sensory neurone → relay neurone → motor neurone → effector
D. Receptor → relay neurone → motor neurone → sensory neurone → effector
C
State the word equation for photosynthesis
CO2 + water (+ light) -> Glucose + Oxygen
State all 7 characteristics of a living organism
Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
Define homozygous and heterozygous
homozygous: both alleles of a gene are the same (aa or AA)
heterozygous: two different alleles make up the genotype (Aa)
Which sequence correctly shows the route of blood from the body to the lungs?
A. Vena cava → right atrium → right ventricle → pulmonary artery
B. Vena cava → left atrium → left ventricle → pulmonary artery
C. Pulmonary vein → right atrium → right ventricle → aorta
D. Aorta → left atrium → left ventricle → pulmonary vein
A - Vena cava → right atrium → right ventricle → pulmonary artery
Which statement correctly compares nervous and hormonal coordination?
A. Both use electrical impulses carried through the blood.
B. Nervous responses are usually faster and shorter-lasting; hormonal responses are usually slower and longer-lasting.
C. Hormonal responses are always faster and shorter-lasting.
D. Nervous coordination uses hormones, while hormonal coordination uses neurones.
B
Which nutrient is needed to make haemoglobin, and what can its deficiency cause?
Iron, anaemia
The scientific names of the lion and tiger are Panthera leo and Panthera tigris. What do these names show?
A. They belong to the same species but different genera.
B. They belong to different genera and different species.
C. They must be able to reproduce together to produce fertile offspring.
D. They belong to the same genus but different species.
D
In a DNA molecule, bonds between pairs of bases hold two strands together. High temperatures can break these bonds to form two single strands of DNA. The base pair C and G is held together more strongly than the base pair A and T. Two DNA molecules containing the same number of bases were studied.
In DNA molecule 1, 20% of bases are T.
In DNA molecule 2, 20% of bases are C.
Which DNA molecule would require the lowest temperature to break into single strands and why?
Molecule 2 because there are more A-T base pairs which are broken more easily.
What happens during normal inspiration?
A. The diaphragm relaxes, thoracic volume decreases and air enters.
B. The diaphragm contracts, thoracic volume decreases and pressure rises.
C. The diaphragm relaxes, thoracic volume increases and pressure falls.
D. The diaphragm contracts, thoracic volume increases and pressure falls.
D - The diaphragm contracts (it lowers), thoracic volume increases and pressure falls, air is drawn in.
A shoot receives light from one side and bends towards it. Explain the mechanism behind it.
Phototropism: Auxin accumulates on the shaded side and stimulates greater cell elongation there, bending the shoot towards the light.
Name the two enzymes needed to break down starch into maltose into glucose
Amylase and maltase
An arthropod has four pairs of legs, no antennae and a body divided into two main regions. Which group does it belong to?
Arachnids
Is it true that we all have the same genes? Explain.
State the BALANCED chemical equation of both aerobic respiration and anaerobic respiration in yeast.
aerobic respiration: C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O (+ 32 ATP)
anaerobic respiration in yeast: C₆H₁₂O₆ → 2 C₂H₅OH + 2 CO₂ (+ 2 ATP)
When blood glucose concentration falls below its normal level, what is the response taken by the pancreas?
The pancreas releases glucagon, causing the liver to break down glycogen and release glucose into the bloodstream, restoring blood glucose concentration
State and briefly describe the 5 stages of digestion
1. Ingestion (taking food and drinks into the body through the mouth)
2. digestion (breaking down the food)
3. absorption (movement of nutrients from the intestines into the blood)
4. assimilation (uptake and use of the nutrients by the cells)
5. egestion (removal of undigested food from the body as feaces)
Two unicellular organisms, X and Y, both have cell walls. X has circular DNA free in the cytoplasm. Y has a nucleus and feeds by secreting enzymes and absorbing the digested nutrients. Which kingdom/s do they belong to?
X- prokaryote
Y- fungi
A tall pea plant (dominant phenotype) has an unknown genotype: TT or Tt. Which cross could reveal its genotype (xTT, xTt, xtt), and what result would confirm this?
Test cross: cross the mystery plant with a recessive plant (tt), therefore, if any offspring is short (recessive), the unknown genotype must have a recessive allele (heterozygous). If no short plants appear, the unknown phenotype must be TT
What happens with respiration when an individual exercises vigorously? Reference anaerobic respiration and oxygen debt.
1- the muscle needs a lot of energy for contraction, which means increased respiration rate and oxygen demand
2- the breathing rate increases but is not enough to supply the oxygen demand so anaerobic respiration happens
3-lactic acid is released as a product of anaerobic respiration, it accumulates and is toxic.
4-lactic acid travels through the blood to the liver where is is broken down by aerobic respiration.
5-the oxygen needed to break down all the lactic acid by aerobic respiration is called oxygen debt
A student shifts their gaze from a distant tree to a nearby book without any change in light intensity. Fill in the blanks:
Ciliary muscles ______ (relax/contract) → suspensory ligaments ______ (slacken/tighten) → lens becomes _______ (thinner/thicker) → ______ (more/less) refraction to the fovea.
The mechanism that allows the eye to focus on far or near objects is called ______.
Ciliary muscles contract → suspensory ligaments slacken → lens becomes thicker → more refraction to the fovea.
The mechanism that allows the eye to focus on far or near objects is called accommodation.
For both pepsin and trypsin, indicate their substrate, product, organ that secretes them, where they act, and the conditions needed for their activity.
Pepsin: proteins, aminoacids, stomach, stomach, acid pH
trypsin: proteins, aminoacids, pancreas, small intestine, alkaline ph
A student uses this key to classify a plant:
| Step | Feature | Go to / Group |
|---|---|---|
| 1a | Produces flowers | Go to 2 |
| 1b | Does not produce flowers; reproduces by spores | Fern |
| 2a | Leaves have parallel veins | Monocotyledon |
| 2b | Leaves have branching veins | Dicotyledon |
The plant is not flowering when observed, but it has leaves with branching veins. Can you identify the plant with this information?
The identification is uncertain: not flowering now does not mean it cannot produce flowers. It could be a fern or a dicotyledon.