MadSci Network: Botany
Query:

Re: What are some similarities between plants and animals?

Date: Wed Dec 5 15:11:27 2001
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 1007563503.Bt
Message:

This is an interesting question that is usually not directly answered in 
biology texts. It can be rather tricky to answer because both the plant and 
animal kingdoms are very diverse, Therefore, it can be hard to make 
generalities. I am including both similarities and differences between plants 
and animals.

Mobility - This one you should be able to determine for yourself.

Pollination - Flowering plants recruit a wide variety of animals, particularly 
insects, to transport their pollen (sperm) by offering them flower nectar and 
pollen as a food reward. Animals do not rely on other species to transfer their 
sperm. 

Seed dispersal - Flowering plants often use animals to disperse their seeds. 
Animals do not usually rely on other organisms to disperse their offspring.

Seeds - Seeds are immature plants with a protective seed coat and a supply of 
nutrients. The immature plants are in suspended animation and may survive tens, 
hundreds or thousands of years before germinating. Some animals, such as birds, 
have eggs, which are somewhat similar to seeds. However, animal eggs are 
nowhere near as tough and long-lived as seeds.

Reproduction - Plants use sexual and asexual reproduction. Higher animals just 
use sexual reproduction.

Male and female - Most plants have both male and female reproductive parts on 
one individual. Individual animals are usually either male or female.

Cloning - Plants often clone themselves and are easily cloned by people via 
rooting cuttings, division, grafting, layering and tissue culture. Higher 
animals are very hard to clone.

Cellular respiration - Used by both and occurs in mitochondria in both.

Mitosis and meiosis - Used by both.

Cells - Both have cells that contain many of the same organelles, such as a 
nucleus.

Cell walls - In plants but not animals.

Cell vacuoles - Major feature of plant cells but not animal cells.

Photosynthesis - Used by most plants. Not done by animals.

Oxygen - Photosynthetic plants produce more oxygen in photosynthesis than they 
use in cellular respiration. Animals produce no oxygen but use oxygen in 
cellular respiration.

Water - Both require water. Land plants require much more water than land 
animals because they transpire most of the water they absorb.

Needs - Plants need only water, carbon dioxide gas, about 14 mineral nutrients, 
and light to produce all the organic compounds they need. Animals need to eat 
other organisms in order to get the organic compounds they require, including 
vitamins, carbohydrates, essential amino acids, essential fatty acids and 
essential minerals.
 
Surface area - Plants have a great surface area relative to their volume to 
maximize interception of light with their leaves and absorption of water and 
mineral nutrients with their roots. Compared to plants, animals usually have a 
much lower surface area relative to their volume.  

Defense - Plants mainly use chemical defenses against animals which try to eat 
them. Their chemical defenses are called secondary compounds. Animals mainly 
use their mobility to avoid getting eaten by other animals. 

Gas exchange - Leaves exchange gases passively through tiny pores called 
stomata. Higher animals have lungs for active gas exchange.

Symbiotic relations - Fungi or nitrogen fixing bacteria often live in plant 
roots. Beneficial bacteria live in animal digestive systems, for example cows 
and termites have bacteria in their stomachs that allow them to digest plant 
cell walls containing cellulose. 

Vision - Plants cannot see like higher animals but can sense light with 
specialized pigments such as phytochrome.

Hearing - Plants do not have hearing ability as many animals do.

Taste - Plants do not have anything similar to a sense of taste that higher 
animals have.

Smell - Plants do not have anything equivalent to a sense of smell as many 
animals do.

Touch - Plants can respond to touch in several ways, termed thigmotropism and 
thigmomorphogenesis. Animals also often respond to touch.

Intelligence - Plants do have brains or thinking ability as humans and some 
animals do.

Hormones - Both have hormones. Plant hormones, such as auxin, ethylene and 
gibberellins, are far less specific in their activities than animal hormones.

Lifespan - Some plants complete their life cycle in one (annuals) or two years 
(biennials). Plants that live for more than 2 years are perennials and some can 
live for thousands of years. Animals, especially insects, may have very short 
live cycles but none live as long as some plants.

Skeletal system - Plants support themselves with their cell walls composed of 
carbohydrates, such as cellulose. Higher animals have a skeleton composed 
mainly of minerals.

Digestive system - Plants do not have a digestive system (stomach, intestines, 
etc.) as do animals.

Wastes - The major waste product of plants is oxygen gas. Animals excrete 
liquid and solid wastes as well as carbon dioxide gas.

Circulatory system - Both have a circulatory system but they are different. 
Plants have xylem for upward transport of water and minerals and phloem for 
moving organic compounds, especially sugars, and some minerals all around the 
plant. Animals often have a circulatory system with a pump (heart) that is also 
usually involved in gas exchange. Plants do not have a pump and do not use 
xylem and phloem for gas exchange.

Immune system - Plants do respond to limit disease damage in specific ways but 
lack the complex immune system of higher animals. 


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