Biology

A study monitored the changes in the body temperature of a kookaburra (an Australian bird) and a human over a 24-hour period. The results of the study are shown in the graph.

Outline an adaptation that may lead to an increase in the kookaburra’s body temperature during the inactive period.

A study monitored the changes in the body temperature of a kookaburra (an Australian bird) and a human over a 24-hour period. The results of the study are shown in the graph.

Some endothermic organisms can display torpor (a significant decrease in physiological activity).
With reference to the graph, explain whether the human or the kookaburra was displaying torpor and if so, state the time this occurred.

Which of the following lists the five steps in the stimulus-response model in the correct order? (A) receptor, stimulus, coordinating centre, effector, response (B) receptor, stimulus, effector, coordinating centre, response (C) stimulus, receptor, coordinating centre, effector, response (D) stimulus, effector, coordinating centre, receptor, response

Birds that live in cold environments have a counter-current heat exchange system in their legs, which is shown in the diagram below. The temperature of the blood is lowest at position
(A) A
(B) B
(C) C
(D) D

Use an example to outline the role of the nervous system in maintaining homeostasis.

Describe TWO mechanisms in plants that allow water balance to be maintained

A healthy person in a hot environment measures their body temperature to be 38.0°C. Which of the following might occur in this person?
A. Shivering
B. Vasodilation
C. Goosebumps
D. Pale appearance

Some desert mammals can obtain their water from breaking down stored body fat. What type of adaptation is this?
A. Behavioural
B. Environmental
C. Physiological
D. Structural

The table below shows the water gained and lost by 2 species of mammals. Which of the following statements is consistent with the given data?
A. The high proportion of water lost through evaporation in species A shows that species A is adapted to survive in a hot and dry climate
B. The higher metabolic rate of species B compared to species A indicates that species B could be a desert animal.
C. 0% water gain and 13.5 ml water loss through urine are indicators of mammal A being a hibernating animal.
D. The overall water gain and loss is higher for mammal B than mammal A, indicating that mammal B has larger surface area.

Glucose levels are maintained by the hormones insulin and glucagon. Which statement best describes the changes in hormone levels of a healthy human soon after a high glucose meal? A. Insulin levels fall and glucagon levels rise. B. Insulin levels fall and glucagon levels fall. C. Insulin levels rise and glucagon levels fall. D. Insulin levels rise and glucagon levels rise.

The graph below shows the relationship between body temperature and environmental temperature of 4 different organisms. Which of the following statements is best supported by the data?
A. Animals I and II are most likely mammals.
B. Animal II is endothermic over the environmental temperature range of 0 to 30°C.
C. Animal III maintains its body core temperature relatively constant by shivering when the environmental temperature falls below 37°C.
D. Animal IV is most likely a mammal in polar region.

The photographs show an open and a closed stomate on a leaf surface. When open, stomates allow water vapour to pass out of the leaf. Regulating stomates is a mechanism by which plants maintain water balance. Which of the following graphs best illustrates this homeostatic mechanism?

Osmoregulation is the process by which water and salt (or solute) concentration in the blood achieves homeostasis using aldosterone and anti-diuretic hormones (ADH). Aldosterone acts on sodium ions causing them to be actively reabsorbed back into the blood from the kidney. As a result, the blood in the capillaries surrounding the kidney’s distal tubule will have a higher solute concentration. An increase in solute concentration in the blood causes the pituitary gland to secrete ADH into the blood stream to increase their permeability of distal tubules to water. This increases the amount of water reabsorbed back into the blood from the kidney. The amount of ADH secreted will decrease when the solute concentration in the blood returns to normality establishing osmoregulation.
A dehydrated marathon runner consumed a concentrated salt sports drink to satisfy his thirst.
How does his body control the two hormones, ADH and aldosterone, to help to re- establish normal water balance?
A. ADH is released and aldosterone is inhibited
B. ADH is inhibited and aldosterone is released.
C. Both ADH and aldosterone are released.
D. Both ADH and aldosterone are inhibited.

Agrobacterium tumefaciens is a rod-shaped bacterium found in soil. Its flagella allow it to move through the soil in response to chemicals released by wounded plant cells. Once it enters its plant host, it injects a section of its DNA called the T-DNA which is derived from its Ti (tumour inducing) plasmid into its host causing the host to form undifferentiated (tumour) tissue termed a crown gall. Figure 1: Crown gall The interaction between a plant and Agrobacterium is detailed below: (A) Agrobacteria cells produce the hormones cytokinin and auxin, which increase host susceptibility and inhibit H2O2 production and hypersensitive response (HR) upon infection. (B) After integration of the bacterial T-DNA into the plant genome, cytokinin and auxin are synthesized by T-DNA encoded enzymes and accumulate inside the tumour. (C) This causes massive changes in the gene expression pattern resulting in metabolomic and morphological adaptations that are necessary for tumour growth and differentiation. (D) Loss of water is minimized by an increase in the levels of the stress hormone ABA. Evaporation of water from the disrupted crown gall surface drives the flow of water and minerals into crown galls. (E) Because photosynthesis is downregulated, the O2 levels are low, the tumour produces C and N compounds heterotrophically and gains energy mainly anaerobically by alcoholic fermentation. (F) The developing tumour becomes a metabolic sink for the host plant, which accumulates metabolites produced by source leaves and minerals taken up by the roots. (G) Auxin and cytokinin also cause an increase in ethylene (ET) which together with salicylic acid (SA) inhibits agrobacterial virulence. (H) ABA induces DNA methylation of the plant genome, regulating gene expression of drought- stress responsive genes. The oncogenes of the T-DNA remain unaffected by methylation of the plant genome.

Identify a mechanism by which the plant maintains homeostasis when infected by agrobacterium.

Outline how in humans, maintenance of temperature is different to the way that glucose is controlled.

The levels of glucose, insulin and glucagon were measured in the plasma of 24 healthy adults at intervals over a 5-hour period. After 1 hour at rest the patients ate a large carbohydrate meal. The results are shown.
Use the data provided to explain how blood glucose is controlled in the body.

The glucose tolerance test is used to investigate the control of glucose in the human body. Patients consume 75 g of glucose and their blood glucose is monitored.
Type 2 diabetes is a condition where the cells of the body do not respond adequately to insulin.
Which graph could represent the results of glucose tolerance tests in a non-diabetic person and a person with untreated Type 2 diabetes?

The diagram shows the effect of the hormone oxytocin on the uterus during the birth of a mammal.

Which of the following best identifies and explains the feedback loop demonstrated in the diagram?

Describe ONE mechanism by which plants maintain internal water homeostasis.