Biology – Patterns in nature –3. Plants and animals have specialized structures to obtain nutrients from their environments

Identify some examples that demonstrate the structural and functional relationships between cell, tissue, organs and organ systems in multicellular organisms.

Cells: basic unit of life

Tissues: Cells with the same specialization

Organs: A collection of tissues which form together to make a specific function.

Organ system: Various organs function together as systems

Example:

Neurone (nerve cell)	Cell
Neurone tissue	Tissue
Brain	Organ
Nervous system	Organ system

 

Distinguish between autotrophs and heterotrophs in terms of nutrient requirements

Autotroph: self feeders – are organisms which make their own foods. Plants are autotrophs and make their own food via photosynthesis.

Heterotrophs: other feeders – are organisms which rely on autotrophs for their food.

*As heterotrophs rely on autotrophs for their food, they gain their nutrients from the nutrients produced by autotrophs.

 

Identify the materials required for photosynthesis and its role in ecosystems

Materials required for photosynthesis:

• Carbon dioxide
  
• Water (from soil)
  
• Energy from sunlight
  
• Chlorophyll
  

Role in ecosystems:

• Provides nutrients for autotrophs and heterotrophs
  
• Provides oxygen for respiration (in mitochondria) in animal cells
  

Identify the general word equation for photosynthesis and outline as a chain of biochemical reactions

Carbon dioxide + water ---light energy--- > glucose + oxygen

Explain the relationship between the organization of structures used to obtain water and minerals in a range of plants and the need to increase surface area available for absorption.

Water is important to plants (and animals) because it is used in every cell to dissolve substances, carry the dissolved substances through the cell membrane and to use them in cell functions. Water loss must be counteracted to ensure that cells have enough liquid, otherwise they will die. Root hairs of roots absorb water from the soil through osmosis, the roots are long and the root hairs extend out through the soil to increase surface area available for water absorption. Minerals, which occur as dissolved ions in the water, absorbed by roots are necessary for organism growth and repair.

Explain the relationship between the shape of leaves, the distribution of tissues in them and their roles.

Flat shape	Large S.A. exposed to sunlight for photosynthesis
Mesophyll Cells	Contain large amounts of chloroplasts, to increase rate of photosynthesis
Stomata	Open and close to limit and increase the rate of gaseous exchange and loss of water
Spongy mesophyll	Creates an internal airspace in which co2 and water can diffuse in and oxygen can diffuse out
Xylem vessels	Transports water to photosynthetic cells
Phloem tissues	Transports products of photosynthesis (sugars)

 

Describe the role of teeth in increasing the surface area of complex foods for exposure to digestive chemicals

The roll of teeth in a digestive system is to break large foods into smaller pieces, increasing S.A and allowing larger exposure to digestive chemicals.

Explain the relationship between length and overall complexity of digestive systems of a vertebrate herbivore and a vertebrate carnivore with respect to: -the chemical composition of their diet, -the functions of the structures involved

Herbivore:

Chemical composition of diet: Mainly cellulose (from plants, found in cell wall), Nutrients are very dispersed and unconsecrated.

Length and complexity: Long digestive system in comparison to carnivores (especially the large intestine and caecum). The long large intestine provides a large surface area to absorb water and minerals. The increased surface area of the caecum provides a large surface area for the bacterial enzymes in the caecum to break down cellulose into less complex minerals. Some mammals (eg: cows) have 4 stomachs, which allow them to break down plant matter more efficiently, others re-digest fecal matter in to digest minerals which didn't have a chance to be absorbed the first time through. Herbivores have a large number of molar teeth which serve to grind down plant material, increasing S.A. for action of enzymes.

Carnivore:

Chemical composition of diet: Mainly protein diet (from tissues in animals), Nutrients are concentrated.

Length and complexity: short system in comparison to herbivores (reduced or no caecum, small long intestine and larger small intestine). The caecum isn't present in many carnivore digestive systems because carnivores do not have cellulose in their diet. The small large intestine is due to the large intestine being for water absorption, and carnivores don't rely on food for water. The larger small intestine serves to give a large area for digestion of food into the bloodstream. Carnivores have a large proportion of canine teeth for tearing flesh.