2021 - JAMB Biology Past Questions and Answers - page 3
chemicals --> olfactory nerve endings --> brain
dissolved chemicals --> nasal sensory cells --> brain
chemicals --> mucus membrane sensory cells --> brain
dissolved chemicals --> sensory cells --> olfactory nerve --> brain
In mammals(humans), the process of olfaction begins when volatile molecules enter the nasal cavity and activate receptors in the olfactory epithelium (OE). The olfactory receptor (OR) proteins are located in hair-like projections of the olfactory sensory neurons (OSNs).
II. Low birth rate and high immigration rate
III. Low mortality rate and low emigration rate
IV. High mortality rate and high emigration rate.
Which combination of the above can cause rapid over-crowding in climax biotic communities and human settlements?
II and III
I and III
I and IV
I and II
Low mortality rate, high birth rate, high immigration rate and low emigration rate are causes for rapid over-crowding.
What is the percentage of occurrence of Imperata spp?
35%
16%
46%
23%
No of Imperata spp = 23
Total plant species = 50
Percentage of imperata spp = \(\frac{23}{50} * 100℅\)
= 46℅
the tank was too small compared to the large-ocean
the body cells of the fish swelled and burst as a result of the hypotonic fresh water
the body cells of the fish shrank as their sap was hypertonic to the freshwater
there was no food in the tank, so the fish starved
Saltwater fish can't survive in freshwater because their bodies are highly concentrated of salt solution (too much for freshwater). The water would flow into their body until all their cells accumulate so much water that they bloat and die eventually.
ATG
TAG
GAT
AGT
The complementary strand for TCA is AGT
| A | T |
| G | C |
| T | A |
| C | G |
| A | T |
| T | A |
| G | C |
| A | T |
Na+ and Fe2+
Mg2+ and K+
Na+ and K+
Fe2+ and Mg2+
The Na⁺ / K⁺ - helps maintain resting potential, affects transport, and regulates cellular volume.
The order of evolutionary advancement of the above vertebrates is?
I, II, III, IV
I, IV, III, II
II, III, IV, I
IV, III, II, I
Evolutionary sequence in vertebrates: Fishes → Amphibians → Reptiles → Birds → Mammals.
IV → III → II → I
Ileum
Pancreas
Gall bladder
Kidney
The pancreas has two main functions: an exocrine function that helps in digestion and an endocrine function that regulates blood sugar.
glomerulus ---> Bowman's capsule -> convoluted tubule ---> Henle's loop -> collecting- tubule
glomerulus -> Bowman's capsule -> convoluted tubule -> Henle's loop -> convoluted tubule -> collecting tubule
convoluted tubule -> glomerulus --> Nettle's loop -> Bowman's capsule->collecting tubule
convoluted tubule -> Bowman's capsule -> Henle's loop -7> glomerulus -> collecting tubule
The kidneys filter unwanted substances from the blood and produce urine to excrete them.
There are three main steps of urine formation: glomerular filtration, reabsorption, and tubular secretion.
These processes ensure that only waste and excess water are removed from the body.
ileum --> caecum ->large intestine -> rectum
ileum --> colon --> caecum -> rectum
large intestine --> ileum -> caecum -> rectum
colon -> caecum -> ileum -> rectum