1. Which of the following is an
excretory organ in flatworms?
A. Malpighian tubules
B. Kidney
C. Nephridium
D. flame cells
Answer: D
A flame cell is a specialized excretory cell found in the simplest freshwater invertebrates, including flatworms, rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia.
2. Which of the following is not
an excretory organ in mammals?
A. Anus
B. Liver
C. Lung
D. Skin
Answer: A
Excretion in Mammals
The four types of excretory organs used by mammals are Lungs, Skin, Liver and Kidney.
The lungs excrete water vapour and carbon(iv)oxide
The Liver excrete bile pigment called Bilirubin. The bilirubin is derived from the decomposition of haemoglobin. The Skin excretes water, salt and urea through sweat while the kidney excrete water, mineral salt, urea, uric acid and creatinine. In mammals, Kidney is the major excretory organ.

3. Which of the following is not
freshwater?
A. Brackish water
B. Puddle
C. Pond
D. River
Answer: A
Brackish water: sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater.
4. Which of the following is a
special organ for oxygen
absorption in aquatic animals?
A. Air bladder
B. Lung
C. Spiracle
D. Gills
Answer: D
Fish and other aquatic organisms use gills to take up oxygen dissolved in the water and diffuse carbon dioxide out of the bloodstream.
5. Drought resistant plants are
called?
A. Hydrophytes
B. Xerophytes
C. Mesophytes
D. Bryophytes
Answer: B
Plants which grow in areas of low rainfall often tolerate drought and are termed xerophytes.