2.18-2.33B - Nutrition

Question 1

What is the definition of Photosynthesis?

Answer 1

The process by which plants manufacture carbohydrates from raw materials using energy from light

Question 2

What occours in the process of photosynthesis?

Answer 2

Energy from sunlight is absorbed by chlorophyll, a green pigment found inside chloroplasts
Green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water
At the same time, oxygen is made and released as a waste product

Question 3

What do plants do?

Answer 3

Autotrophs – they can make complex molecules (glucose) from simple molecules (carbon dioxide and water)
Producers - they can make their own food and so are the first organism at the start of all food chains

Question 4

What were the products of photosynthesis?

Answer 4

Plants use the glucose they make as a source of energy in respiration
They can also use it to
Produce starch for storage
Synthesise lipids for an energy source in seeds
To form cellulose to make cell walls
Produce amino acids (used to make proteins) when combined with nitrogen and other mineral ions absorbed by roots

Question 5

What is the photosynthesis word equation?

Answer 5

Question 6

What is the balanced symbol equation for photosynthesis?

Answer 6

Question 7

What are all of the factors affecting the rate of photosynthesis?

Answer 7

So a limiting factor can be defined as something present in the environment in such short supply that it restricts life processes
There are three main factors that limit the rate of photosynthesis:
Temperature
Light intensity
Carbon dioxide concentration

Question 8

Why is water needed for photosynthesis?

Answer 8

Although water is necessary for photosynthesis, it is not considered a limiting factor as the amount needed is relatively small compared to the amount of water transpired from a plant so there is hardly ever a situation where there is not enough water for photosynthesis
The number of chloroplasts or the amount of chlorophyll in the chloroplasts can also affect the rate of photosynthesis

Question 9

How does tempreture affect the rate of photosynthesis?

Answer 9

The temperature of the environment affects how much kinetic energy all particles have – so temperature affects the speed at which carbon dioxide and water move through a plant
The lower the temperature, the less kinetic energy particles have, resulting in fewer successful collisions occurring over a period of time
Increasing temperature increases the kinetic energy of particles, increasing the likelihood of collisions between reactants and enzymes which results in the formation of products
At higher temperatures, however, enzymes that control the processes of photosynthesis can be denatured (where the active site changes shape and is no longer complementary to its substrate) – this reduces the overall rate of photosynthesis

Question 10

How does light intensity affect the rate of photosynthesis?

Answer 10

The intensity of the light available to the plant will affect the amount of energy that it has to carry out photosynthesis
The more light a plant receives, the faster the rate of photosynthesis
This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply

Question 11

How does carbon dioxide concentration affect the rate of photosynthesis

Answer 11

Carbon dioxide is one of the raw materials required for photosynthesis
This means the more carbon dioxide that is present, the faster the reaction can occur
This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply

Question 12

How does chlorophyll affect the rate of photosynthesis?

Answer 12

The number of chloroplasts (as they contain the pigment chlorophyll which absorbs light energy for photosynthesis) will affect the rate of photosynthesis
The more chloroplasts a plant has, the faster the rate of photosynthesis
The amount of chlorophyll can be affected by:
Diseases (such as tobacco mosaic virus)
Lack of nutrients (such as magnesium)
Loss of leaves (fewer leaves means fewer chloroplast

Question 13

Give the structure of the leaf

Answer 13

Question 14

Give the structure of the lead

Answer 14

Question 15

What are the specialised

Answer 15

Question 16

What are mineral ions and how are they produced?

Answer 16

Photosynthesis provides a source of carbohydrates, but plants contain and require many other types of biological molecule; such as proteins, lipids and nucleic acid (DNA)
As plants do not eat, they need to make these substances themselves
Carbohydrates contain the elements carbon, hydrogen and oxygen but proteins, for example, contain nitrogen as well (and certain amino acids contain other elements too)
Two fundamental mineral ions required by plants are nitrogen and magnesium, without a source of these elements, plants cannot photosynthesise or grow properly
Plants obtain these elements in the form of mineral ions actively absorbed from the soil by root hair cells
‘Mineral’ is a term used to describe any naturally occurring inorganic substance

Question 17

What are problems Mineral ion and nitrate ion deficiency ?

Answer 17

Question 18

What does a balance diet consist of?

Answer 18

A balanced diet consists of all of the food groups in the correct proportions
The necessary key food groups are:
Carbohydrates
Proteins
Lipids
Dietary Fibre
Vitamins
Minerals (mineral ions)
Water

Question 19

What is malnutrition?

Answer 19

Question 20

What are the different food groups what are their functions and what are their sources?

Answer 20

Question 21

What are the different vitamins their functions and their sources?

Answer 21

Question 22

What are the variations in Dietary?

Answer 22

Question 23

What is digestion?

Answer 23

Digestion is a process in which relatively large, insoluble molecules in food (such as starch, proteins) are broken down into smaller, soluble molecules that can be absorbed into the bloodstream and delivered to cells in the body.

Question 24

What are the small soluble molecules used for in the body?

Answer 24

These small soluble molecules (such as glucose and amino acids) are used either to provide cells with energy (via respiration), or with materials with which they can build other molecules to grow, repair and function

Question 25

How is the alimentary canal?

Answer 25

The human digestive system is made up of the organs that form the alimentary canal and accessory organs
The alimentary canal is the channel or passage through which food flows through the body, starting at the mouth and ending at the anus
Digestion occurs within the alimentary canal
Accessory organs produce substances that are needed for digestion to occur (such as enzymes and bile) but food does not pass directly through these organs

Question 26

Where are all the Alimentary canal located in the body?

Answer 26

Question 27

What role does the Mouth and salivary glands have in the Alimentary canal?

Answer 27

Mouth/ Salivary glands - The mouth is where mechanical digestion takes placed chewing food to break it down into smaller pieces and increase its surface area to volume ratio. Amylase enzymes in saliva starts digesting starch into maltose. Theo food is lubricated in saliva so can be swallowed

Question 28

What role does the oesophagus have in the Alimentary canal?

Answer 28

Tube that connects the mouth to the stomach where the food bolus goes after being swallowed wave - pushing the food bolus down.

Question 29

What role does the stomach have in the Alimentary canal?

Answer 29

Food is mechanically digested by churning actions while protease enzymes start to chemically digest proteins hydrochloric acid is present to kill bacteria in food providing optimum pH for protease enzymes to work

Question 30

What is the role of the small intestine have in the Alimentary canal?

Answer 30

First section called the Duodenum and is where the food coming out the stomach finishes being digested by enzymes produced here and also secreted from the pancreas
pH of the small intestine is alkaline pH 8-9
Second section called ileum and is where absorption of digested food molecules takes place, the ileum is long and lined with villi to increase surface area over which absorption can take place

Question 31

What is the role of the large intestine have in the Alimentary canal?

Answer 31

Water is absorbed from remaining material in colon to produce faeces
Faeces is stored in the rectum and removed through anus

Question 32

What is the role of the pancreas in the Alimentary canal?

Answer 32

Produces all 3 types of digestive enzymes, amylase protease and lipase
secreted enzymes in an alkaline fluid into the duodenum for digestion to raise the pH of fluid coming out the stomach.

Question 33

What is the role of the liver in the Alimentary canal?

Answer 33

Produces Bile to emulsify fats like mechanical digestion Amino Acids used to make proteins broken down producing urea.

Question 34

What is the role of the Gall bladder in the Alimentary canal?

Answer 34

Stores Bile to release into Duodenum as required

Question 35

What are the stages of food break down?

Answer 35

Ingestion - the taking in of substances, e.g. food and drink, into the body through the mouth
Mechanical digestion - the breakdown of food into smaller pieces without chemical change to the food molecules
Chemical digestion - the breakdown of large, insoluble molecules into small, soluble molecules
Absorption - the movement of small food molecules and ions through the wall of the intestine into the blood
Assimilation - the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
Egestion - the passing out of food that has not been digested or absorbed (as faeces) through the anus

Question 36

What is peristalses?

Answer 36

Peristalsis is a mechanism that helps moves food along the alimentary canal

Question 37

What is the stages of peristalses?

Answer 37

Firstly, muscles in the walls of the oesophagus create waves of contractions which force the bolus along
Once the bolus has reached the stomach, it is churned into a less solid form, called chyme, which continues on to the small intestine
Peristalsis is controlled by circular and longitudinal muscles
Circular muscles contract to reduce the diameter of the lumen of the oesophagus or small intestine
Longitudinal muscles contract to reduce the length of that section the oesophagus or the small intestine
Mucus is produced to continually lubricate the food mass and reduce friction
Dietary fibre provides the roughage required for the muscles to push against during Peristalsis

Question 38

What is the purpose of digestion?

Answer 38

The purpose of digestion is to break down large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream
Food is partially digested mechanically (by chewing, churning and emulsification) in order to break large pieces of food into smaller pieces of food which increases the surface area for enzymes to work on

Question 39

What role do enzymes have in digestion?

Answer 39

Digestion mainly takes place chemically, where bonds holding the large molecules together are broken to make smaller and smaller molecules
Chemical digestion is controlled by enzymes which are produced in different areas of the digestive system
Enzymes are biological catalysts – they speed up chemical reactions without themselves being used up or changed in the reaction
There are three main types of digestive enzymes – carbohydrates, proteases and lipases

Question 40

What role do carbohydrase have in digestion?

Answer 40

Carbohydrases are enzymes that break down carbohydrates to simple sugars such as glucose
Amylase is a carbohydrase which is made in the salivary glands, the pancreas and the small intestine
Amylase breaks down starch into maltose
Maltase then breaks down maltose into glucose

Question 41

What role does Proteases have in digestion?

Answer 41

Proteases are a group of enzymes that break down proteins into amino acids
Pepsin is an enzyme made in the stomach which breaks down proteins into smaller polypeptide chains
Proteases made in the pancreas and small intestine break the peptides into amino acids

Question 42

What role does lipase have in digestion?

Answer 42

Lipases are enzymes that break down lipids (fats) to glycerol and fatty acids
Lipase enzymes are produced in the pancreas and secreted into the small intestine

Question 43

What is bile?

Answer 43

Bile is an alkaline substance produced by cells in the liver
Before being released into the small intestine bile is stored in the gallbladder

Question 44

What are the roles of bile?

Answer 44

Neutralising the hydrochloric acid from the stomach
The alkaline properties of bile allow for this to occur
This neutralisation is essential as enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach
Breaking apart large drops of fat into smaller ones (and so increasing their surface area)
This is known as emulsification
The more alkaline conditions and larger surface area allows lipase to chemically break down the fat (lipids) molecules into glycerol and fatty acids at a faster rate

Question 45

What are the adaptions of the small intestine?

Answer 45

The small intestine is adapted for absorption as it is very long and has a highly folded surface with millions of villi (tiny, finger-like projections)
These adaptations massively increase the surface area of the small intestine, allowing absorption to take place faster and more efficiently
Peristalsis helps by mixing together food and enzymes and by keeping things moving along the alimentary canal
Villi of the small intestine
Villi have several specific adaptations which allow for the rapid absorption of substances:
A large surface area
Microvilli on the surface of the villus further increase the surface available for absorption
A short diffusion distance
The wall of a villus is only one cell thick
A steep concentration gradient
The villi are well supplied with a network of blood capillaries that transport glucose and amino acids away from the small intestine in the blood
A lacteal (lymph vessel) runs through the centre of the villus to transport fatty acids and glycerol away from the small intestine in the lymph
Enzymes produced in the walls of the villi assist with chemical digestion
The movement of villi helps to move food along and mix it with the enzymes present