2.2. Carbohydrates and lipids
A subsection of Biology, 9700, through 2. Biological molecules
Listing 10 of 368 questions
Hummingbirds are the smallest of birds and are found in the Americas. Some species migrate hundreds of kilometres between warmer overwintering areas and summer breeding grounds. Like mammals, birds maintain a constant body temperature. Hummingbirds have a high requirement for sugars because they have a very high metabolic rate. shows a hummingbird feeding on nectar, one of their main food sources. Nectar is a sugary liquid containing mainly sucrose, fructose and glucose. Sucrose has the molecular formula C12H22O11. Fructose and glucose each have the molecular formula C6H12O6. State two differences between sucrose and fructose, other than the number of carbon, hydrogen and oxygen atoms present. In preparation for migration, sugars need to be converted to triglycerides to function as energy reserves. Hummingbirds can double their body mass during this time. shows the structural formula of one type of storage triglyceride. The triglyceride has two types of fatty acid residue, palmitate and oleate. H H C O O C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H palmitate oleate H C O O C H H C H H C H H C H H C H H C H H C H H C H C H C H H C H H C H H C H H C H H C H H C C H H H H C H C H H H H C H H C O O C H H C H H H C H H C H H C H H C H H C H H C H C H C H H C H H C H H C H H C H H C H H C Outline the features of the molecular structure of the triglyceride shown in . In hummingbirds, glycogen is the long-term carbohydrate energy store. Suggest one reason why hummingbirds build up a greater energy store in the form of triglyceride, rather than a greater energy store of glycogen, in preparation for migration. In birds such as hummingbirds: • blood is kept within vessels • for each complete circuit of the body, blood passes through the heart twice. State the term used to describe this type of circulatory system. The heart of birds has the same structure as the heart of mammals. Compared with the heart of mammals, the heart of birds is larger in proportion to their body size. Suggest why the heart of birds is larger in proportion to their body size. Complete Table 3.1 to show the names and functions of the main blood vessels associated with the heart of mammals. Table 3.1 function of blood vessel name of blood vessel carries blood from the heart to the lungs carries blood to the heart from the lungs carries blood from the heart to the rest of the body carries blood to the heart from the rest of the body
9700_s22_qp_22
THEORY
2022
Paper 2, Variant 2
View
Questions Discovered
368